Important Questions

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 11 Transport in Plants Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 11 Transport in Plants

Very short answer type questions

Question 1.
Define translocation.
Answer:
Transport over longer distances proceeds through the vascular system (the xylem and the phloem) and known as translocation.

Question 2.
Osmosis is a special kind of diffusion, in which water diffuses across the cell membrane. The rate and direction of osmosis depends upon both. [NCERT Exemplar]
Answer:
Pressure and concentration gradient.

Question 3.
The plant cell cytoplasm is surrounded by both cell wall and cell membrane. The specificity of transport of substances are mostly across the cell membrane, because. [NCERT Exemplar]
Answer:
The cell wall is freely permeable to water and other substances in the solution but the plasma membrane is selectively permeable.

Question 4.
Why does rate of transport reach maximum or becomes saturated in facilitated diffusion?
Answer:
The transport rate reach a maximum because all the transport proteins are occupied/saturated.

Question 5.
Imbibition is considered a method of diffusion. Comment.
Answer:
Imbibition is considered as a method of diffusion because the movement of water occurs along the concentration gradient during this process.

Question 6.
Give one basic difference between antiport and uniport.
Answer:
In antiport both the molecules cross the membrane in opposite directions whereas, in uniport molecules moves across a membrane independent of any other passing molecule.

Question 7.
Mention two .factors on which net direction of molecules and rate of osmosis depends.
Answer:
The two factors responsible are:

1. Pressure gradient
2. Concentration gradient.

Question 8.
A flowering plant is planted in an earthen pot and irrigated. Urea is added to make the plant grow faster, but after sometime the plant dies. This may be due to which factor? [NCERT Exemplar]
Answer:
As urea content make the soil hypertonic in nature, therefore, the plant dies due to exosmosis.

Question 9.
The endodermis is impervious to water. Comment.
Answer:
The inner boundary of the cortex, i.e., endodermis is impervious to water because of a band of suberised matrix called the casparian strip.

Question 10.
Identify the vascular tissue responsible for translocation of organic and inorganic substances from leaves to other parts of the plant.
Answer:
Phloem is responsible for this type of translocation.

Question 11.
How do root hairs increase the absorption of water by plants?
Answer:
Root hairs increase the surface area of roots. This helps in making contact with larger volume of water. Thus, the presence of root hairs helps in absorption by plants.

Question 12.
It is seen that the number of stomata are greater on the lower surface of the leaf than the upper surface. Why is it so ?
Answer:
Stomata are present in greater number on the lower surface because if more number of stomata will be present on the upper surface, it would lead to great amount of water loss through transpiration. Thus, to avoid the excessive transpiration, stomata are present in greater number on lower surface of the leaf.

Question 13.
Elucidate the channels of food transport in plants.
Answer:
The channels of food transport are sieve tubes and sieve cells of phloem.

Question 14.
How are companion cells helpful to sieve tubes?
Answer:
The companion cells are connected to the sieve tubes by plasmodesmata and provide them with proteins, ATP and other nutrients.

Short answer type questions

Question 1.
Define facilitated diffusion.
Answer:
Membrane proteins provide sites at which movement of certain molecules takes place. These molecules have hydrophilic moiety and hence it is difficult for them to cross a membrane. They- need assistance of membrane proteins to cross the membrane. This is called facilitated diffusion.

Question 2.
Give a comparison table of different transport mechanisms.
Answer:
Comparison of Different Transport Mechanisms

Question 3.
Photosynthesis needs constant supply of water. But transpiration can hamper this supply. How do plants of desert area manage to get sufficient water in spite of faster transpiration?
Answer:
Desert plants have a different mechanism of photosynthesis and it is called C₄ pathways. The evolution of the C₄ photosynthetic system is probably one of the strategies for maximising the availability of CO₂ while minimising water loss. C₄ plants are twice as efficient as C₃ plants in terms of fixing carbon (making sugar). However, a C 4 plant loses only half as much water as a C₃ plant for the same amount of CO₂ fixed.

Question 4.
What is the significance of transpiration?
Ans. Significance of Transpiration

• Transpiration pull facilitates movement of water from roots.
• Transpiration supplies water for photosynthesis.
• It pulls minerals from soil.
• Helps in cooling of plants.
• Maintains shape of plant cells.

Question 5.
Describe the movement of water in leaves.
Answer:
Evaporation from the leaf sets up a pressure gradient between the outside air and the air spaces of the leaf. The gradient is transmitted into the photosynthetic cells and on the water-filled xylem in the leaf vein. This facilitates movement of water from xylem to the guard cells of stomata.

Long answer type questions

Question 1.
Observe the given figure and answer the following questions:

(i) State the nature of solution marked (1).
(ii) What process has been depicted in figures C to D?
(iii) In which figures turgor pressure will be zero?
(iv) In which figures wall pressure will he positive?
Answer:
(i) The solution marked as (1) will he hypertonic (more concentrated) due to which cell shrinks.
(ii) From C to D, figure is showing the process of deplasmolysis as shrinked cell has again regained its original shape.
(iii) Turgor pressure will be zero in figure B and C because cell is in a flaccid condition.
(iv) Wall pressure will be positive in figure A and D because in these figure cell wall is exerting ‘equal and opposite pressure against the expanding protoplasm.

Question 2.
Minerals are present in the soil in sufficient amount. [NCERT Exemplar]
(i) Do plants need to adjust the types of solute that reach xylem.
(ii) Which molecules help to adjust this?
Answer:
(i) An analysis of the xylem exudates shows that though some of the nitrogen travels as inorganic ions, much of it is carried in the organic form as amino acids and related compounds. Similarly, small amount of P and | S are carried as organic compounds. In addition, small amount of exchange of materials does take place between xylem and phloem.

(ii) Mineral ions are frequently remobilised, particularly from older, sensecing parts. Older dying leaves export much of their mineral content to younger leaves. Similarly, before leaf fall in deciduous plants, minerals are removed to other parts. Elements most readily mobilised are phosphorus, sulphur, nitrogen and potassium. Some elements that are structural components like calcium are not remobilised.

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 10 Cell Cycle and Cell Division Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 10 Cell Cycle and Cell Division

Very short answer type questions

Question 1.
During which phase of mitotic cell division, chromosomes gets separated?
Answer:
During anaphase.

Question 2.
Does mitosis occurs before or after the interphase?
Answer:
Yes, mitosis occurs before or after the interphase, as dividing phase (meiosis or mitosis) and interphase are considered only as the major phases of a cell cycle.

Question 3.
Mitosis cell division helps in regeneration process. How?
Answer:
Mitosis helps in regeneration by keeping all the somatic cells of an organism genetically similar, so that they are able to regenerate part or whole of the organism.

Question 4.
Given that average duplication time of E. coli is 20 minutes. How much time will two E. coli cells take to become 32 cells?
Answer:
2 hours (2ⁿ = 2⁵ = 2 × 2 × 2 × 2 × 2 = 32 generations).

Question 5.
If a tissue has 1024 cells at a given time, how many cycles of mitosis had the original parental single cell undergone?
[NCERT Exemplar]
Answer:
10 (2ⁿ, where n =10 generations).

Question 6.
Two key events take place during S-phase in animal cells, i.e., DNA replication and duplication of centriole. In which parts of the cell do these events occur? [NCERT Exemplar]
Answer:
DNA replication in the nucleus. Centriole duplication in the cytoplasm.

Question 7.
At what stage of meiosis, formation of tetrads occurs? Name it.
Answer:
Tetrads are formed during pachytene of prophase-I (meiosis-I).

Question 8.
Meiosis is essential in sexually reproducing organisms. How?
Answer:
Meiosis is essential in sexually reproducing organisms because it keeps the chromosome number constant.

Question 9.
Which cells of our body do not divide?
Answer:
Neuron cells stops dividing soon after the birth of a child.

Question 10.
The diagram shows a bivalent at prophase-I of meiosis. Which of the four chromatids can cross over? [NCERT Exemplar]
Answer:
The non-sister chromatids of homologous pair of chromosome undergo meiosis.

Short answer type questions

Question 1.
Imagine a situation if there was no meiosis. Then what would have happened to the next generation?
Answer:
In the absence of meiosis the next generation would have double the number of chromosomes after fusion of gametes. This would have resulted in the birth of an altogether new species. The maintenance of characters set would have been possible only through asexual reproduction.

Question 2.
Give a description of metaphase I of meiosis.
Answer:
Metaphase I: The bivalent chromosomes align on the equatorial plate. The microtubules from the opposite poles of the spindle attach to the pair of homologous chromosomes.

Question 3.
Describe telophase I of meiosis.
Answer:
Telophase I

• The nuclear membrane and nucleolus reappear, cytokinesis follows and this is called as diad of cells.
• Although in many cases the chromosomes do undergo some dispersion, they do not reach the extremely extended state of the interphase nucleus.
• The stage between the two meiotic divisions is called interkinesis and is generally short lived. Interkinesis is followed by prophase II, a much simpler prophase than prophase I.

Question 4.
What is the process of cell division in prokaryotes?
Answer:
Prokaryotes do not have nucleus. So, there is no elaborate karyokinesis, as seen in eukaryotes. In prokaryotes the replication of DNA starts the process of cell division. Once genetic material is replicated, it is followed by division of cytoplasm. The process is known as binary fission.

Question 5.
How does meiosis facilitate creation of offsprings, with distinct characters?
Answer:
Meiosis happens during gametogenesis and as a result gametes have half the number of chromosomes. During fertilization, when gametes fuse together two different sets of chromosomes make a new set. This results in an offspring, who has distinct characters, compared to parents.

Question 6.
What is the significance of mitosis?
Answer:
Significance of Mitosis

• In multicellular organisms, body growth is by mitotic divisions of the cells.
• Replacement of worn out tissues/cells (e.g., blood cells, skin cells) and repair of the injured tissues is by mitosis.
• In unicellular organisms, mitosis are involved in asexual reproduction
  (multiplication of cells).
• In plants, vegetative propagation involves only mitotic divisions and genetically identical individuals are produced.
• Uncontrolled cell divisions in certain tissues/organ (cancer) result in tumours.

Long answer type questions

Question 1.
Briefly describe the significance of cell division.
Answer:
Cell division is significant in the following ways :

• Cell Multiplication: Cell division is a means of cell multiplication or formation of new cells from pre-existing cells.
• Continuity: It maintains continuity of living matter generation after generation.
• Multicellular Organisms: The body of a multicellular organism is formed of innumerable cells. They are formed by repeated divisions of a single cell or zygote. As the number of cells increases, many of them begin to differentiate, form tissues and organisms.
• Cell Size: Cell division helps in maintenance of a particular cell size which is essential for efficiency and control of cell activities.
• Genetic Similarity: The common type of cell division or mitosis maintains genetic similarity of all the cells in an individual despite being different, i.e., structurally and functionally.

Question 2.
Explain meiosis-II in an animal cell.
Answer:
All these happen in the two haploid nuclei simultaneously.

• Prophase-II: It takes short time. Spindle formation begins and the chromosomes become short. Two chromatids, are joined to a single centromere. Nuclear membrane and nucleolus disintegrate.
• Metaphase-II: At the equator, the chromosomes lie and spindle is formed. The centromere of every chromosomes is joined to the spindle fibre and centromere also divides.
• Anaphase-II: The daughter chromosomes are formed. Chromatids move towards their poles with the spindle fibres.
• Telophase-II: Reaching at the poles, chromosomes form nuclei which are haploid (n) daughter nuclei. Again nuclear membrane is constructed. Nucleolus now becomes clearly visible.
• Cytokinesis: It occurs and four daughter cells are formed which are haploid (n). It may occur once or twice (i.e., in meiosis-I and II) or only after the meiosis-II cell division.

Question 3.
Describe briefly the phases of meiotic division.
Answer:
Meiotic division takes place in germ cells. The number of chromosomes is reduced to half in daughter cells.

Meiotic cell division is divided into two phases, i.e., meiotic-I and II.
In the meiotic-I division, the homologous chromosomes pair to form bivalent. Exchange of genetic material takes place. The chromosomes now separate and get distributed into daughter cells.

Long prophase-I is divided into five sub-stages, i.e., leptotene, zygotene, pachytene, diplotene and diakinesis. During metaphase-I, the bivalents arrange themselves on equatorial plate with their arms on the plate but the centromere is directed towards opposite pole. It is followed by anaphase-I. Now, the homologous chromosomes repel each other, move to the opposite poles with both their chromatids. In this way each pole gets half the chromosomes number of the parent cell.

In telophase-I, the nuclear envelope and nucleolus again appear. The centromere of each chromosome breaks, separating the chromatids, one each to a daughter cell. The meiotic cell division maintains chromosome number of a species.

As a result of meiotic division, the four daughter cells are formed with half the chromosome number (haploid) in each cell.

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 14 Respiration in Plants Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 14 Respiration in Plants

Very short answer type questions

Question 1.
Why does anaerobic respiration/fermentation yields less energy than aerobic respiration?
Answer:
It happens due to incomplete oxidation of the substrate.

Question 2.
Write the overall equation of respiration.
Answer:
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy

Question 3.
Name two openings in plants through which exchange of gases takes place?
Answer:
Stomata and lenticels.

Question 4.
Write the reaction where substrate-level phosphorylation takes place in glycolysis.
Answer:
Substrate level phosphorylation takes place during the following reaction

• When 1, 3-bisphosphoglycerate is converted into 3-phosphoglycerate.
• When phosphoenolpyruvate is converted into pyruvic acid.

Question 5.
List two instances where lactic acid is formed by fermentation.
Answer:
Instances, where lactic acid is formed by fermentation, are given below:

1. During fermentation by lactic acid bacteria.
2. During strenuous exercise, in the striated muscles in humans.

Question 6.
Mention the step of citric acid cycle, which is not mediated by dehydrogenase enzyme.
Answer:
Conversion of oxaloacetic acid to citric acid is not mediated by dehydrogenase enzyme.

Question 7.
At which step of respiration, hydrogen of NADH₂ is used?
Answer:
The hydrogen atoms accepted by NADH₂ during glycolysis are introduced to route I of ETS. In this route 3 ATP molecules are produced.

Question 8.
Mention the number of protons that passes through complex V for the synthesis of 2 molecules of ATP.
Answer:
Two pairs of protons (i.e., 4) passes through complex V for the synthesis of two molecules of ATP.

Question 9.
Name the inhibitor of oxidative phosphorylation.
Answer:
Oligomycin.

Question 10.
Name the unit of oxidative phosphorylation.
Answer:
Oxysomes.

Question 11.
F₀ – F₁ particles participate in the synthesis of ……………………. [NCERT Exemplar]
Answer:
ATP (Adenosine Triphosphate), the energy currency of the cell.

Question 12.
What do you mean by respiratory balance sheet?
Answer:
Respiratory Balance Sheet
The calculations of the net gain of ATP for every glucose molecule oxidized, can be made only on certain assumptions.
But this kind of assumptions are not valid in a living system for the following reasons :

• All pathways work simultaneously and do not take place one after the other.
• Substrates keep entering the pathways and are also withdrawn from the pathways.
• ATP is utilized as and when needed,
• Rates of enzyme actions are controlled by multiple means.

Short answer type questions

Question 1.
Why ATP is called an energy currency?
Answer:
The energy produced during various steps of cellular respiration is stored in the form of ATP. This is later utilized on an SOS basis. So, ATP is also called as energy currency.

Question 2.
There is no special respiratory organ in plants, yet plants efficiently manage exchange of gases. Justify.
Answer:
Every part of plant manages its gas exchange need. There is no exchange of gases between different organs. So unlike animals plants do not need special respiratory organs to facilitate exchange of gases. In leaves the exchange of gases takes place through stomata, while in stems it takes place through lenticels.

Question 3.
How glycolysis takes place in anaerobic environment?
Answer:
Glycolysis is the breakdown of glucose into pyruvic acid and it does not need oxygen. So in all living beings, irrespective of them being either aerobic or anaerobic glycolysis takes place. In fact glycolysis is the first step towards oxidation of glucose and oxidation takes place either during anaerobic respiration or during aerobic respiration.

Question 4.
The maximum concentration of alcohol produced by natural fermentation is 13%. But most of the alcoholic preparations for human consumption contain more than this percentage. How this higher percentage is achieved?
Answer:
The higher percentage of alcohol is achieved through distillation of the liquid, which gives pure alcohol as well. The boiling involved in distillation helps evaporate the liquid part and higher concentration is achieved.

Long answer type questions

Question 1.
Oxygen is critical for aerobic respiration. Explain its role with respect to ETS.
Answer:

• Oxygen is an essential requirement for aerobic respiration because an element of strong electronegativity to pull the electrons down the chain is needed.
• It ensures that protons are pumped into the outer lumen of the mitochondria, where they can come down their concentration gradient through ATP-synthase making ATP.
• The oxygen picks up electrons and protons, thus forming water. As the electrons in the ETS are used to do work, the electrons lose energy and reach a point at the end of the ETS, where they have to be gotten rid of.
• The scheme the cell uses to do this is to combine the electrons with hydrogen ions and oxygen to produce water.

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 9 Biomolecules Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 9 Biomolecules

Very short answer type questions

Question 1.
Write the name of any one amino acid, sugar, nucleotide and fatty acid. [NCERT Exemplar]
Answer:
Alanine is an amino acid, glucose is a sugar, adenylic acid is a nucleotide and linolenic acid is a fatty acid.

Question 2.
Mention four essential major elements of life.
Answer:
Oxygen, carbon, hydrogen and nitrogen are the four essential elements of life.

Question 3.
Name one element invariably found in proteins but not in all carbohydrates and lipids.
Answer:
Nitrogen is found invariably in proteins, but not in all carbohydrates and lipids.

Question 4.
What is the name given to a polysaccharide composed of two different monomers? Also give example for this.
Answer:
The name given is heteropolysaccharide to the type of polysaccharide, which is composed of different types of monomers, e.g., Pectin.

Question 5.
One of the homopolysaccharide is also known as animal starch. Name it.
Answer:
Glycogen is also known as animal starch.

Question 6.
The macromolecules that forms the hereditary determinants of the living organism. Name it.
Answer:
Nucleic acid.

Question 7.
A nitrogenous base is present in RNA but absent in DNA. Name it. Also give example in which it exists.
Answer:
Uracil (U), is the nitrogenous base present only in RNA, e.g., viruses like hepatitis C.

Question 8.
How many hydrogen bonds are formed between:
(i) Guanine and cytosine
(ii) Adenine and thymine, respectively?
Answer:
(i) Three hydrogen bonds between guanine and cytosine.
(ii) Two hydrogen bonds between adenine and thymine.

Question 9.
Reaction given below is catalysed by oxidoreductase between two substrates A and A, complete the reaction. [NCERT Exemplar] A reduced + A oxidised →
Answer:
A reduced + A’ oxidised → A oxidised + A’ reduced + A’ reduced

Question 10.
Name two physical factors which can affect the enzyme activity?
Answer:
Temperature and pH are the two physical factors that affects activity of an enzyme.

Question 11.
The enzyme that works only in the presence of a co-factor or coenzyme called
Answer:
Apoenzyme works only in the presence of a co-factor or coenzyme.

Question 12.
What do you mean by living state?
Answer:
The living state is a non-equilibrium steady-state to be able to perform work.

Short answer type questions

Question 1.
Give a tabular representation of different constituents of a living cell.
Answer:

Component	% of Total Cellular Mass
Water	70-90%
Proteins	10-15%
Carbohydrates	3%
Lipids	2%
Nucleic Acids	5-7%
Ions	1%

Question 2.
What are polysachharides?
Answer:
Polysaccharides are long chains of sugars. They are threads containing different monosaccharides as building blocks.

In a polysaccharide chain (say glycogen), the right end is called the reducing end and the left end is called the non-reducing end. Starch forms helical secondary structures. In fact, starch can hold 12 molecules in the helical portion.
Examples: Cellulose, chitin

Question 3.
Give a brief description of nucleic acid.
Answer:
For nucleic acids, the building block is a nucleotide. A nucleotide has three chemically distinct components. One is a heterocyclic compound, the second is a monosaccharide and the third is a phosphoric acid or phosphate.

The heterocyclic compounds in nucleic acids are the nitrogenous bases named adenine, guanine, uracil, cytosine, and thymine. Adenine and Guanine are substituted purines while the rest are substituted pyrimidines. The skeletal heterocyclic ring is called as purine and pyrimidine respectively. The sugar found in polynucleotides is either ribose (a monosaccharide pentose) or 2’ deoxyribose. A nucleic acid containing deoxyribose is called deoxyribonucleic acid (DNA) while that which contains ribose is called ribonucleic acid (RNA).

Question 4.
What is the difference between primary and secondary metabolites?
Answer:
Primary metabolites are found in both, animal cells and plant cells. Secondary metabolites are found only in plant cells.
Functions of primary metabolites are known to scientists, while functions of secondary metabolites are not known yet.

Question 5.
Explain the basic structure of an amino acid.
Answer:

Amino acid is an organic compound, which has an amino group and an acidic group, present
as substituents on the same carbon ; i.e., the a-carbon. Because of this amino acids are also called α-amino acids. On four valency positions there are four substituent groups. They are hydrogen, carboxyl group, amino group and a variable group. The variable group is called the ‘R’ group. The nature of R group decides the type of an amino acid.

Question 6.
Describe the classification and nomenclature of enzymes.
Answer:
Classification and Nomenclature of Enzymes: The International Union of Biochemists (IUB) has classified all the enzymes into the following six classes:

(a) Class 1: Oxidoreductases: These enzymes catalyse the oxidation (by adding oxygen or removal of hydrogen or removal of electrons) or reduction (by adding hydrogen or adding electrons to a substrate) of a substance.
S reduced + S’ oxidised → S oxidised + S’ reduced

(b) Class 2: Transferases: These enzymes catalyse the transfer of specific groups from one substrate to another. S – G + S’ → S + S’ – G.

(c) Class 3: Hydrolases: These enzymes catalyse the breakdown of larger molecules into smaller molecules with the addition of water.

(d) Class 4: Lyases: These enzymes catalyse the cleavage of specific covalent bonds and removal of specific group (s), without the use of water.

(e) Class 5: Isomerases: These enzymes catalyse the rearrangement of atoms in a molecule to form isomers.

(f) Class 6: Ligases: These enzymes catalyse covalent bonding (of C-0, C-S, C-N, P-O etc.) between two substrates to form a large molecule, mostly involving utilisation of energy by hydrolysis of ATP.

Long answer type questions

Question 1.
Enumerate the difference between a nucleotide and nucleoside. Give two examples of each with their structure. [NCERT Exemplar]
Answer:
Differences between nucleotide and nucleoside are given below:

Nucleotide	Nucleoside
A nucleotide consists of a nitrogenous base, a sugar (ribose or deoxyribose) and one to three phosphate groups, i. e., sugar + base + phosphate.	A nucleoside consists of a nitrogenous base t covalently attached to a sugar (ribose or deoxyribose), but without the phosphate group, i. e., sugar + base

Question 2.
What is the concept of metabolism? What are the metabolic basis for living?
Answer:
The continuous process of breakdown and synthesis of biomolecules through chemical reactions occurring in the living cells is called metabolism.

• Each of the metabolic reaction results in a transformation of biomolecules.
• Most of these metabolic reactions do not occur in isolation but are always linked with some other reactions.
• In these reactions, the metabolites are converted into another metabolite in a series of linked reactions called metabolic pathways.
• Each metabolite has a definite rate and direction during the flow through a metabolic pathways called the dynamic state.

In living systems, metabolism involves two following types of pathways:
(a) The anabolic pathway is called biosynthetic pathway. It leads to a more complex structure from a simpler structure, e.g., The pathway involving the conversion of acetic acid into cholesterol. These pathways consume energy.

(b) The catabolic pathways lead to simpler structure from a complex structure, e g., The pathway involving conversion of glucose into lactic acid in our skeletal muscles. This pathway lead to the release of energy, e.g., Energy is liberated when glucose is degraded to lactic acid in our skeletal muscles.

Question 3.
Formation of Enzyme-Substrate complex (ES) is the first step in catalysed reactions. Describe the other steps till the formation of product.
Answer:
Mechanism of Enzymatic Action: The catalytic cycle of an enzyme action can he described in the following steps :

• First, the substrate binds to the active site of the enzyme, fitting into the active site.
• The binding of the substrate induces the enzyme to alter its shape, fitting more tightly around the substrate. The formation of the ES complex is essential for catalysis.
  E + S → ES → EP → E + P
• The active site of the enzyme, now in close proximity of the substrate breaks the chemical bonds of the substrate and the new enzyme product complex is formed.
• The enzyme releases the products of the reaction and the free enzyme is ready to bind to another molecule of the substrate and run through the catalytic cycle one again.

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 15 Plant Growth and Development Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 15 Plant Growth and Development

Very short answer type questions

Question 1.
Identify the actively dividing cells in plants.
Answer:
Meristems are the actively dividing cells present in the plants.

Question 2.
What happens if the meristematic cells ever cease to divide?
Answer:
If meristematic cells cease to divide, the growth of the plant will be hindered and will undergo a period of dormancy depending upon the seasonal changes in the climate. „

Question 3.
Growth is one of the characteristics of all living organisms? Do unicellular organisms also grow? If so, what are the parameters?
Answer:
Yes, unicellular organisms also grow. Their cell size increases up to a certain fixed dimension only.

Question 4.
Mention the name of the internal factors that control development in plants.
Answer:
Internal factors that control development in plants are as follows:

1. Genetic factors (intracellular)
2. Plant growth regulators (intercellular).

Question 5.
Identify the plant hormone-related with intermodal elongation.
Answer:
Gibberellin is the plant hormone-related with internodal elongation.

Question 6.
Mention the name the growth regulator, which was first isolated from endosperm of maize. Give its main biological activity.
Answer:
Zeatin is the growth regulator isolated from endosperm of maize. It controls cell division (cytokinesis) even in non-meristematic tissues.

Question 7.
In most plants, the terminal bud suppresses the development of lateral buds into branches. What is this phenomenon called? Name one phytohormone that can promote this phenomenon.
Answer:
The phenomenon is called apical dominance. Auxin is the phytohormone involved in prompting this phenomenon.

Question 8.
Which air pollutant also acts as a plant hormone?
Answer:
Ethylene.

Question 9.
How do gibberellin help in promoting seed germination?
Answer:
The gibberellin mobilize storage reserves by amylases during germination of seeds.

Question 10.
What are the plant organs responsible for the perception of light variation? What is the pigment responsible for this perception?
Answer:

• Leaves are mainly responsible for perception of light intensity in plants.
• The pigment that performs this perception is called phytochrome.

Question 11.
Name the hormones involved in photoperiodism.
Answer:
Florigen is the hormone involved in photoperiodism.

Question 12.
Beetroot is often known as a long-day plant. Explain why?
Answer:
Beetroot is known as long-day plant because flowering takes place when the plants are exposed to day length longer than a critical period.

Short answer type questions

Question 1.
An owner of an apple orchard wants to get better yield and wants to wait for good market conditions to sell his apples. Which PGR should he use to achieve his goals?
Answer:
He should use Gibberellins. Gibberellins help increase the size of apples. Moreover, they also delay senescence so apples can be left on branches for a longer duration. This will give the orchard owner enough time to wait for good market conditions.

Question 2.
What are plasticity and heterophylly?
Answer:
In some plants, certain structures show different forms, in response to environment or to phases of life. This ability is known as plasticity.

For example, in cotton, coriander, and larkspur, leaves of juvenile plants are different in shape compared to leaves in mature plants. This is called heterophylly. Juvenile In buttercup shape of leaves produced in air is different from that produced in water.

Question 3.
What are the favorable conditions for seed germination?
Answer:
Favorable conditions for seed germination are given below:

• Proper temperature
• Moisture
• Sunlight
• Oxygen.

Question 4.
What are the various man-made meant of overcoming seed dormancy?
Answer:
Man-made means of overcoming seed dormancy are given below :
The seed-coat barrier in some seeds can be broken by mechanical abrasions using knives, sandpaper, etc. or by vigorous shaking.

Effect of inhibitory substances can be removed by subjecting the seeds to chilling conditions or by application of certain chemicals like gibberellic acid and nitrates. Changing environment conditions: like light and temperature.

Question 5.
What do you understand by apical dominance?
Answer:
In most of the higher plants, growing apical bud inhibits the growth of lateral (axillary buds). This phenomenon is called apical dominance. Removal of short tips (decapitation) normally results in the growth of lateral buds. Decapitation is used in tea plantations to get more leaves from a plant.

Long answer type questions

Question 1.
Mention the phenomenon of growth in plants. Explain the phases of growth in detail.
Answer:
Growth is defined as a permanent or irreversible increase in dry weight, mass or volume of cell, organ or organism.
Plant growth takes place in three steps or phases cell, division (meristematic), cell elongation and cell maturation.
(i) Cell Division (Meristematic) Phase:

• It is also called formative phase.
• New cells are produced by mitotic divisions of the pre-existing cells. The meristematic cells have thin cellulose walls with abundant plasmodesma connections, dense protoplasm and conspicuous nuclei.
• In higher plants cell division occurs in meristems or growing points.
• As the formation of new cells requires intense biosynthetic activity, the rate of respiration in the cells of formation phase is very high.

(ii) Cell Elongation Phase:

• It is also called phase of cell enlargement.
• This phase lies just behind the growing points and is mainly responsible for growth of plant parts.
• The newly formed cells, produced informative phase undergo enlargement.
• The cell walls of the enlarging of cell show plastic extension through enzymatic loosening of microfibrils and deposition of new materials.
• The enlarging cell also develops a central vacuole, rate of respiration is high but less than that of the cells in the formative phase.
• Thus, this phase is characterized by cell enlargement, new cell wall deposition and increased vacuolation.

(iii) Cell Maturation Phase

• This phase occurs just behind the phase of elongation.
• The enlarged cells develop into particular type of cells by undergoing structural and physiological differentiation.
• Hence, at this phase, all the diverse tissue types observed in root or stem.

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 8 Cell: The Unit of Life Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 8 Cell: The Unit of Life

Very short answer type questions

Question 1.
Give one difference between the characteristic feature of Gram positive and Gram negative bacteria.
Answer:
Gram positive bacteria retain crystal violet dye and stain blue in colour, while Gram negative bacteria loose dye colour on washing.

Question 2.
What is the name given to the infoldings of plasmalemma in fungal cell below the wall?
Answer:
Mesosomes.

Question 3.
What does ‘S’ refers in a 70S and 80S ribosome? [NCERT Exemplar]
Answer:
The ‘S’ refers to Svedberg units of sedimentation coefficient. The sedimentation coefficient is a measure of the speed of the sedimentation for a particular cell organelle in ultracentrifuge.

Question 4.
What are inclusion bodies?
Answer:
Reserve material in prokaryotic cells are stored in the cytoplasm in the form of inclusion bodies.

Question 5.
In which organelle the proteins required for functioning of nucleus are formed?
Answer:
Proteins required are formed in cytoplasm.

Question 6.
Which is considered to be the main arena of cellular activities in plant and animal cells?
Answer:
Cytoplasm is considered to be the main arena of cellular activities.

Question 7.
Mention a single membrane bound organelle, which is rich in hydrolytic enzymes. [NCERT Exemplar]
Answer:
Lysosome.

Question 8.
What is the significance of vacuole in a plant cell? [NCERT Exemplar]
Answer:
The vacuole in a plant cell helps to maintain osmotic pressure for turgidity and osmosis. It also stores useful as well as waste substances.

Question 9.
Why are the mitochondria and plastids called semi-autonomous particles?
Answer:
These are called so, because they are not dependent upon nuclear DNA and cytoplasmic ribosomes for the synthesis of proteins, while other organelles are dependent.

Question 10.
What is referred to as satellite chromosome? [NCERT Exemplar]
Answer:
Sometimes, few chromosomes have non-staining secondary constrictions at a constant location. This gives appearance of a small fragment called satellite. The chromosome having satellite are known as satellite chromosomes.

Question 11.
What do you meant by 9+2 pattern of organisation?
Answer:
It means that 9 microtubule doublets surround two single microtubules.

Question 12.
Define the microbodies.
Answer:
Membrane bound minute vesicles that contain various enzymes are called microbodies. These are present in both plant and animal cells.

Short answer type questions

Question 1.
Differentiate between prokaryotic and eukaryotic cells.

Prokaryotic Cell	Eukaryotic Cell
•» Nuclear membrane absent	Nuclear membrane present
•» Cell organelles absent (except ribosome)	Cell organelles present
•» Endomembrane system absent	Endomembrane system present
•» Example: bacteria	Example: RBC, neuron

Question 2.
Describe passive transport, osmosis and active transport in plasma membrane.
Answer:
Passive Transport: The plasma membrane is selectively permeable to some molecules present on either side of it. Many molecules can move briefly across the membrane without any requirement of energy and this is called the passive transport.

Osmosis: Neutral solutes may move across the membrane by the process of simple diffusion along the concentration gradient, i.e., from higher concentration to the lower. Water may also move across this membrane from higher to lower concentration. Movement of water by diffusion is called osmosis.

Active Transport: As the polar molecules cannot pass through the nonpolar lipid bilayer, they require a carrier protein of the membrane to facilitate their transport across the membrane. A few ions or molecules are transported across the membrane against their concentration gradient, i.e., from lower to the higher concentration. Such a transport is an energy dependent process, in which ATP is utilised and is called active transport, e.g., Na⁺/K⁺ Pump.

Question 3.
What is endomembrane system in a cell?
Answer:
Certain cell organelles function in coordinated manner. Their v coordination makes the endomembrane system of cell. Following structures comprise the endomembrane system:

• Endoplasmic Reticulum
• Golgi Complex
• Lysosome, and
• Vacuoles.

Question 4.
Cells in the epithelial tissue are held together with very little intercellular material (matrix). Specialised junctions provide both structural and functional links between individual cells. Three types of cell junctions have been recognised.
(a) Name the three types of cell junctions and write their functions.
(b) What value is shown by such an arrangement?
Answer:
(a) The three types of cell junctions are:

1. Tight junctions,
2. Gap junctions and
3. Adhering junctions

Functions of cell junctions are ‘

• Tight junctions prevent the leaking of substances across a tissue.
• Gap junctions facilitate the cells to communicate with each other by connecting their cytoplasm.
• Adhering junctions perform cementing of the adjacent cells to keep them together.

(b) No individual can function alone in a society. We need some form of interaction and help from others; so lend a helping hand to the needy.

Question 5.
Give a brief description of ribosomes.
Answer:
Ribosomes are the granular structures first observed under the electron microscope as dense particles by George Palade (1953). They are composed of ribonucleic acid (RNA) and proteins and are not surrounded by any membrane. The eukaryotic ribosomes are 80S while the prokaryotic ribosomes are 70S. Here ‘S’ stands for the sedimentation coefficient; it indirectly is a measure of density and size. Both 70S and 80S ribosomes are composed of two subunits.

Question 6.
Write a short note on-
(i) Cytoskeleton,
(ii) Cilia & Flagella
Answer:
(i) Cytoskeleton: An elaborate network of filamentous proteinaceous structures present in the cytoplasm is collectively referred to as the cytoskeleton. The cytoskeleton in a cell are involved in many functions such as mechanical support, motility, maintenance of the shape of the cell.

(ii) Cilia and Flagella: Cilia (sing.: cilium) and flagella (sing.: flagellum) are hair-like outgrowths of the cell membrane. Cilia are small structures which work like oars, causing the movement of either the cell or the surrounding fluid. Flagella are comparatively longer and responsible for cell movement. The prokaryotic bacteria also possess flagella but these are structurally different from that of the eukaryotic flagella.

Long answer type questions

Question 1.
Write the functions of the following: [NCERT Exemplar]
(i) Centromere
(ii) Cell wall
(iii) Smooth ER
(iv) Golgi apparatus
(v) Centrioles
Answer:
(i) Functions of Centromere
(a) It is a narrow non-stainable area which join chromatids together to form a chromosome.
(b) The centromere thus, keep the two chromatids of a chromosome in an intact stage.
(c) This is an essential step for chromosomes of a cell during cell division whether it may be mitosis or meiosis.

(ii) Functions of Cell Wall
(a) It helps in providing a definite shape to the cell and also protects protoplasm against any mechanical injury, i.e., damage and infection.
(b) It also helps in cell-to-cell interaction.
(c) It provides barrier to undesirable macromolecules and attack of pathogens.

(iii) Functions of Smooth Endoplasmic Reticulum
(a) It provides mechanical support to colloidal complex of cytoplasmic matrix.
(b) It holds various cell organelles in position.
(c) It conducts information from outside to inside of cell.

(iv) Functions of Golgi Apparatus
(a) It performs the function of packaging material.
(b) It acts as an important site for the formation of glycoproteins and glycolipids.
(c) It helps in the production of complex carbohydrates other than glycogen and starch.
(d) It helps in the formation of cell wall.

(v) Functions of Centrioles
(a) Formation of new centrioles from pre-existing one’s during cell division.
(b) They form basal bodies, which in turn form cilia and flagella.
(c) They form spindle fibres that give rise to spindle apparatus during cell division .in animal cells.

Question 2.
Is there a species or region specific type of plastids? How does one distinguish one from the other? [NCERT Exemplar]
Answer:
Plastids are both region or species specific. These are as follows :
(i) Proplastids: These are colourless, rounded but amoeboid plastid precursors, found in meristematic and newly formed cells of plants. It has a double membrane envelope that surrounds a colourless matrix, containing DNA, ribosomes and reserve food. A few vesicles and lamellae also occur in the matrix.

(ii) Leucoplasts: These are colourless plastids that occur in non-green plant cells commonly near the nucleus. They are as follows:
(a) Amyloplasts: These leucoplasts store starch, e.g., tuber of potato, grain of rice and wheat.
(b) Elaioplasts: These store fats, e.g., Rose.
(c) Aleuroplasts: They are protein storing plastids, e.g., Castor endosperm.

(iii) Chromoplasts: These are non-photosynthetic coloured plastids which synthesise and store carotenoid pigments. They appear, orange, red or yellow in colour. These mostly occur in ripe fruits (tomato and chillies) carrot roots, etc.

(iv) Chloroplasts: These are photosynthetic plastids, which are green in colour and found in the leaves of all green plants. They have lamellae organised in the form of grana.

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 7 Structural Organisation in Animals Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 7 Structural Organisation in Animals

Very short answer type questions

Question 1.
A muscular fibre tapers at both the ends and does not show striations. Name the muscle fibre. [NCERT Exemplar]
Answer:
Smooth or non-striated muscle fibre.

Question 2.
Name few called the specialised connective tissues?
Answer:
Bones, cartilage and blood are the special types of connective tissues.

Question 3.
How does a gap junction facilitate the intercellular communication? [NCERT Exemplar]
Answer:
A gap junction facilitates the cells to communicate with each other by connecting the cvtoplasm of the adjacent cells.

Question 4.
Which tissue forms the ligaments? What is their function?
Answer:
Ligaments are formed of yellow elastic connective tissue. The ligaments join the bones together.

Question 5.
On which segment of the body, male and female genital apertures are present in earthworm?
Answer:
Male – 18th segment; Female – 14th segment.

Question 6.
Why the body segmentation in earthworm is called metameric segmentation ?
Answer:
In metameric segmentation, the external segmentation corresponds to the internal segmentation of the body.

Question 7.
In earthworm, from which segment intestine starts and where it ends?
Answer:
In earthworm, intestine starts from the 15th segment onwards and continues till the last segment.

Question 8.
Where the sclerites are present in cockroach? [NCERT Exemplar]
Answer:
In the exoskeleton all over the body.

Question 9.
Which month part of cockroach is comparable to our tongue? [NCERT Exemplar]
Ans.
Hypopharynx.

Question 10.
Name the upper lip and lower lip of the cockroach.
Answer:
Upper lip – Labrum
Lower lip – Labium

Question 11.
Why the blood of cockroach is not responsible for transporting respiratory gases?
Answer:
Because the respiratory pigment is absent in their blood.

Question 12.
List the parts of blood vascular system of cockroach.
Answer:
Haemocoel, heart and blood.

Short answer type questions

Question 1.
Answer:

Smooth Muscle	Skeletal Muscle	Cardiac Muscle
1. Spindle shaped cells	Striated unbranched cells	Striated branched cells
2. Found in muscles of internal organs	Found	Found in the heart
3. Control involuntary actions	Control voluntary actions	Control heart’s pumping which is involuntary

Question 2.
What do you understand by special junctions between cells? Which type of special junction are found in epithelial tissues?
Answer:
All cells are held together with intercellular material. These materials form junctions between cells.
There are three types of cell junctions found in epithelial tissue.
(a) Tight Junctions: These junctions help in stopping leakage of substances across a tissue.
(b) Adhering Junctions: These junctions keep neighbouring cells together.
(c) Gap Junctions: These junctions connect cytoplasm of adhering cells, and facilitate exchange of materials.

Question 3.
Explain fertilization and development in Pheretima.
Answer:
Fertilization and Development in Pheretima

• A mutual exchange of sperm occurs between two worms during mating. One worm has to find another worm and they mate juxtaposing opposite gonadal openings exchanging packets of sperms called spermatophores.
• Mature sperm and egg cells and nutritive fluid are deposited in cocoons produced by the gland cells of clitellum. Fertilisation and development occur within the cocoons which are deposited in soil.
• The cocoon holds the worm embryos. After about 3 weeks each cocoon produces two to twenty baby wopns with an average of four. Earthworms development is direct, i.e., there is no larva formed.

Question 4.
Describe mouth parts of the cockroach. ,
Answer:
Mouth Parts of Cockroach: Anterior end of the head bears appendages forming biting and chewing type of mouth parts. The mouth ‘ parts consist of following structures:
(a) Labrum (upper lip),
(b) A pair of mandibles,
(c) A pair of maxillae and
(d) Labium (lower lip).
Apart from these a median flexible lobe, acting as tongue (hypopharynx), lies within the cavity enclosed by the mouth parts.

Question 5.
Explain in brief the nervous system of cockroach.
Answer:
Nervous System of Cockroach

• The nervous system of cockroach consists of a series of fused, segmentally arranged ganglia joined by paired longitudinal connectives on the ventral side.
• Three ganglia lie in the thorax, and six in the abdomen. The nervous system of cockroach is spread throughout the body.
  The head holds a bit of a nervous system while the rest is situated along the ventral (belly-side) part of its body.

Question 6.
Explain digestion in frogs.
Answer:
Digestion in Frog

• In the stomach digestion of food takes place by the action of HCl and gastric juices secreted from the walls of the stomach.
• Partially digested food called chyme is passed from stomach to the first part of the intestine, the duodenum. The duodenum receives bile from gall bladder and pancreatic juices from the pancreas through a common bile duct.
• Bile emulsifies fat and pancreatic juices digest carbohydrates and proteins. Final digestion takes place in the intestine.
• Digested food is absorbed by the numerous finger-like folds in the inner wall of intestine called villi and microvilli.

Question 7.
Explain in brief the central nervous system of frog.
Answer:
Central Nervous System of Frog ,

• Brain is enclosed in a bony structure called brain box or skull (cranium).
• The brain is divided into fore-brain, mid-brain and hind-brain.
• Forebrain includes olfactory lobes, paired cerebral hemispheres and unpaired diencephalon.
• The midbrain is characterised by a pair of optic lobes.
• Hind-brain consists of cerebellum and medulla oblongata.
• The medulla oblongata passes out through the foramen magnum and continues into spinal cord, which is enclosed in the vertebral column.
• There are ten pairs of cranial nerves arising from the brain.

Question 8.
How do different senses work in frog? Explain in brief. ,
Answer:
Sense Organs in Frog : Frog has different types of sense organs which are as follows:
(a) Sensory papillae or organs of touch,
(b) Taste buds.
(c) Nasal epithelium for the sense of smell,
(d) Eyes for vision and
(e) Tympanum ‘with internal ears for hearing.

Out of these, eyes and internal ears are well-organised structures and the rest are cellular aggregations around nerve endings. Eyes in a frog are a pair of spherical structures situated in the orbit in skull. These are simple eyes. External ear is absent in frogs and only tympanum can be seen externally. The ear is an organ of hearing as well as balancing.

Long answer type questions

Question 1.
Which features distinguish blood from lymph?
Answer:
Differences between blood and lymph are given below :

Blood	Lymph
1. It contains plasma, erythrocytes, leucocytes and platelets.	It contains plasma and leucocytes.
2. The presence of haemoglobin imparts red colour to it.	It is colourless as haemoglobin is absent.
3. Its plasma contains more protein, calcium and phosphrous as compared to lymph.	Its plasma has fewer protein and less calcium and phosphorus than blood.
4. Contains moderate amount of CO2 and other metabolic waste.	Contains excessive amount of CO2 and other metabolic waste.

Question 2.
In which segment does the following structures lies in the earthworm’s body?
(i) Spermathecae
(ii) Pharynx
(iii) Gizzard
(iv) Intestine
(v) Septal nephridia
(vi) Ovary
(vii) Testes
(viii) Typhlosole
(ix) Lateral heart
(x) Pharyngeal nephridia
Answer:
(i) Spermathecae – 6th, 7th, 8th, 9th
(ii) Pharynx – 4th
(iii) Gizzard – 8th
(iv) Intestine – 15th to last
(v) Septal nephridia – 15th to last
(vi) Ovary – 13th
(vii) Testes – 10th, 11th
(viii) Typhlosole – 26th-95th
(ix) Lateral heart – 7th, 9th
(x) Pharyngeal nephridia – 4th-6th

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 16 Digestion and Absorption Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 16 Digestion and Absorption

Very short answer type questions

Question 1.
What do we call the type of teeth attachment in which each tooth, is embedded in a socket of jaws bones? [NCERT Exemplar]
Answer:
Thecodont dentition.

Question 2.
Out of the three types of salivary glands, which is situated in the upper palate on either side of cheek.
Answer:
Parotid gland (type of salivary gland) is situated in the upper palate on the either side of the cheek.

Question 3.
If a person is suffering from reflux oesophagitis, which part of his alimentary canal is not functioning properly?
Answer:
In reflux oesophagitis, the oesophagus does not function properly.

Question 4.
HCl is secreted in stomach. Give the name of the cells that secrete it.
Answer:
Oxyntic cells (parietal cells) are the stomach epithelial cells, that secretes gastric acid, i.e., HCl.

Question 5.
Crypts of Lieberkuhn are found in which part of the alimentary canal.
Answer:
These are found in small intestine portion of alimentary canal.

Question 6.
Give the name of the enzymes involved in the breakdown of nucleotides into sugars and bases? [NCERT Exemplar]
Answer:
Nucleosidases.

Question 7.
Trypsinogen is an inactive enzyme of pancreatic juice. An enzyme, enterokinase activates it. Which tissue/cells secrete this enzyme? How is it activated? [NCERT Exemplar]
Answer:
The cells of duodenum secrete enzyme enterokinase. It is activated by food in the duodenum.

Question 8.
Mention the function of saliva other than digestion.
Answer:
Apart from taking part in digestion, saliva also helps to lubricate the food for swallowing.

Question 9.
State the source of trypsin and the food constituent which this enzyme hydrolyses.
Answer:
Pancreatic juice is the source of trypsin which hydrolyses proteins into peptides.

Question 10.
If the bile duct is completely blocked. How would it affect the digestion of food?
Answer:
If the bile duct is blocked completely, the bile will fail to reach the small intestine and the digestion of fats gets affected.

Question 11.
By which type of mechanism, amino acids are absorbed in our body?
Answer:
Small amounts of amino acids are absorbed by active transport and some are absorbed by the facilitated transport.

Question 12.
As fatty acids and glycerol are not absorbed directly. Name the form in which fatty acids are converted to get absorbed?
Answer:
Fatty acids and glycerols are not absorbed directly into the bloodstream. Thus, they are absorbed in the form of small droplets called micelles.

Question 13.
Which type of absorption takes place in large intestine?
Answer:
Absorption of water, some minerals and drugs takes place in the large intestine.

Question 14.
What happens in the condition when bile from the liver crystalises?.
Answer:
When bile from the liver get crystallised, person form stones in the body.

Short answer type questions

Question 1.
What is the role of tongue indigestion?
Answer:
Tongue helps in mixing the food properly with salivary enzymes. Moreover, tongue has tastebuds which give the sense of different tastes. Eating is a complex process which needs involvement of olfactory and visual senses as well. Alongwith tongue all these senses help in picking the right food.

Question 2.
What is the function of large intestine?
Answer:
Functions of large intestine are as follows:

• Absorption of some water, minerals and certain drugs.
• Secretion of mucus. Mucus helps in adhering the waste particles together and lubricates it for easy passage.

Question 3.
What is digestive waste and how is it removed from the body?
Answer:
After digestion and absorption of food is over the residue left makes the digestive waste. The digestive wastes, solidified into coherent faeces in the rectum initiate a neural reflex causing an urge or desire for its removal. The egestion of faeces to the outside through the anal opening (defaecation) is a voluntary process and is carried out by a mass peristaltic movement.

Question 4.
How does the nervous system control the activities of gastrointestinal tract?
Answer:
The sight, smell and/or presence of food in the oral cavity can stimulate the secretion of saliva. Gastric and intestinal secretions are also stimulated by similar neural signals. Muscular activities of alimentary canal is coordinated by both local and CNS neural mechanisms. Hormonal control of secretion of digestive enzymes is carried out by local hormones.

Question 5.
Write a short note on-Disorders of digestive system.
Answer:
Disorders of Digestive System
(i) Inflammation of intestinal tract
This is the most common disorder of the digestive system.
It is caused by infections by bacteria or viruses and also by parasites like roundworm, hookworm, pinworm, etc.

(ii) Jaundice
It is the infection and inflammation of the liver.
Bile pigments are present in the blood and cause yellowing Of eyes, skin, etc.

(iii) Vomiting
It is the egestion of contents of the stomach through the mouth.

(iv) Diarrhoea
The abnormal frequency of bowel movement and increased liquidity of the faecal discharge is known as diarrhoea.
It reduces the absorption of food.

(v) Constipation
In constipation, the faeces are retained within the rectum as the bowel movements occur irregularly.

(vi) Indigestion
In indigestion, the food is not properly digested leading to a feeling of fullness.
The causes of indigestion are inadequate enzyme secretion, anxiety, food poisoning, overeating, spicy food, etc.

Long answer type questions

Question 1.
As a result of intestinal disease, parts of the alimentary canal are sometimes surgically removed. Discuss the effect of this removal on lifestyle and digestive function:
(i) the stomach
(ii) the colon.
Answer:
(i) Removal of the stomach, which is the main organ for digestion of protein, leads to a change in the patient’s diet. It is the stomach where proteins are first broken down into polypeptides by pepsin in gastric juice before they can be acted on by pancreatic enzymes and intestinal enzymes. The patient must lower down the amount of protein in his diet. Animal meat especially red meat, which is rich in proteins must be avoided.

(ii) Removal of the colon, which is responsible for absorption of water from undigested food, result in loss of water (dehydration) inpatient. The patient needs to drink plenty of fluids to replace water loss. In most cases, where the whole colon is removed, a surgical procedure.is done to attach the small intestine to the rectum to allow for recta elimination of liquid stools. A small pouch is created in the lower abdomen to collect the stool. The patient has to learn to regulate his bowel movements.

Question 2.
A person had roti and dal for his lunch. Trace the changes that will take place during its complete passage through the alimentary canal. [NCERT Exemplar]
Answer:
Changes that will take place in food (roti and dal) through the passage of alimentary canal are given below:

• The food substances are first masticated by the teeth in the mouth, where carbohydrate part of the food is digested by the action of salivary amylase enzyme secreted by the salivary glands.
• This partially digested food reaches the stomach, where it receives acidic HCl and mainly the protein part of the food is digested by the action of proteolytic enzymes.
• The lipid part of the food is digested by the bile secreted by the gall bladder.
• In the small intestine, particularly in the duodenum, this semi-digested food is finally digested by the digestive enzymes present in the intestinal and pancreatic juices.
• After digestion, the broken down products of food, i.e., amino acids, glycerol, starch, etc., are observed mainly in the small intestine.
• The undigested remains of food will finally pass through the anus.

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 6 Anatomy of Flowering Plants Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 6 Anatomy of Flowering Plants

Very short answer type questions

Question 1.
The product of photosynthesis is transported from the leaves to various parts of the plant and stored in some cells before being utilised. What are the cells/tissues that store them?
Answer:
Parenchyma.

Question 2.
What is the function of phloem parenchyma? [NCERT Exemplar]
Answer:
It takes part in lateral conduction of food and supply of water from xylem.

Question 3.
What is the epidermal cell modification in plants which prevent [NCERT Exemplar]
Answer:
Cuticularised trichoblasts or epidermal hair which produce a stationary layer of air over the surface that reduces isolation and rate of transpiration.

Question 4.
The cells of this tissue are living and show angular wall thickenings. They also provide mechanical support. The tissue is: [NCERT Exemplar]
(a) xylem
(b) sclerenchyma
(c) collenchyma
(d) epidermis
Answer:
(c) The collenchyma is a simple permanent tissue, which provide mechanical support.

Question 5.
In which vascular bundles, phloem lies on the outer side and xylem towards the inner side or central axis?
Answer:
Collateral vascular bundles.

Question 6.
What is present on the surface of the leaves which helps the plant prevent loss of water but is absent in roots? [NCERT Exemplar]
Answer:
Cuticle layer and wax.

Question 7.
What constitutes the cambial ring? [NCERT Exemplar]
Answer:
Fusion of interfascicular and intrafascicular cambium strips.

Question 8.
The cross-section of a plant material showed the following features when viewed under the microscope (a) Vascular bundles were radially arranged (b) Four xylem strands with exarch condition of protoxylem. To which organ should it be assigned? [ NCERT Exemplar]
Answer:
Dicot root.

Question 9.
What do hardwood and softwood stand for? [NCERT Exemplar]
Answer:
Hardwood contains xylem vessels, i.e., dicot wood. Softwood contains tracheids only, i. e., gymnospermous wood.

Question 10.
Give one basic functional difference between phellogen and phelloderm.
Answer:
Phellogen is meristematic and divides to produce new cells. Phelloderm stores food materials.

Short answer type questions

Question 1.
Differentiate among parenchyma, collenchyma and sclerenchyma.

Parenchyma	Collenchyma	Sclerenchyma
1. Living cells.	1. Living cells.	1. Dead cells.
2. Forms	2. Found below epidermis.	2. Usually found in epidermis.
3. Chloroplast present.	3. Chloroplast present sometimes.	3. Chloroplast absent.
4. Performs many vital functions.	4. Provides mechanical support to growing parts.	4. Provides mechanical support to organs.

Question 2.
Mention key differences between xylem and phloem.
Answer:
Differences between xylem and phloem

Xylem	Phloem
1. Composed of tracheids, vessels and xylem parenchyma.	1. Composed of sieve tubes, companion cells and phloem parenchyma.
2. Facilitate conduction of water and minerals from roots.	2. Facilitate conduction of food from leaves.

Question 3.
What is the difference between simple tissue and complex tissue in plants?
Answer:
Simple tissues are composed of similar cells. Complex tissues are composed of dissimilar cells. Simple tissues provide bulk and mechanical support to plants. Complex tissues are meant for transportation of substances and they also provide mechanical support.

Question 4.
What is the difference between monocot and dicot leaves?
Answer:
Stomata are found on both surfaces in monocot leaves, while they are found on ventral surface only, in dicot leaves. In monocot leaves venation is parallel, which is evident by similar size of vascular bundles. In dicot leaves venation is reticulate, so vascular bundles are of various sizes.

Question 5.
What are the differences between meristematic tissues and permanent tissues?
Answer:
Differences between meristematic tissues and permanent tissues

Meristematic Tissues	Permanent Tissues
1. Cells keep on dividing.	1. Cells stop dividing.
2. Growth is the basic function.	2. Protection is the basic function.
3. Found in tips of roots and stem.	3. Found in girth and periphery.

Long answer type questions

Question 1.
Distinguish between following:
(i) Exarch and endarch condition of protoxylem
(ii) Stele and vascular bundles
(iii) Protoxylem and metaxylem
(iv) Interfascicular cambium and intrafascicular cambium
(v) Open and closed vascular bundles
(vi) Stem hair and root hair [NCERT Exemplar]
Answer:
(i) In exarch condition protoxylem towards the periphery. In endarch
condition protoxylem towards the centre.
(ii) Stele is the arrangement of vascular tissues and vascular bundle is a group of xylem and phloem.
(iii) Protoxylem is an early formed xylem and metaxylem is late formed xylem.
(iv) Interfascicular cambium is formed by permanent tissues. Intrafascicular cambium is present in between the primary xylem and primary phloem of a vascular bundle.
(v) Open vascular bundles have intrafascicular cambium and show secondary growth. Closed vascular bundles do not have intrafascicular cambium.
(vi) Stem hair are multicellular, whereas root hair are unicellular.

Punjab State Board PSEB 11th Class Biology Important Questions Chapter 17 Breathing and Exchange of Gases Important Questions and Answers.

PSEB 11th Class Biology Important Questions Chapter 17 Breathing and Exchange of Gases

Very short answer type questions

Question 1.
Why do cells need a constant supply of oxygen?
Answer:
Cells continuously need oxygen for the metabolic reactions that releases energy from molecules. This energy is used by cells for various functions of body.

Question 2.
Give the name of the organ that produces sound.
Answer:
Larynx.

Question 3.
A fluid filled double membranous layer surrounds the lungs. Name it. [NCERT Exemplar]
Answer:
This layer is called pleural membrane and pleural fluid is found in between the two.

Question 4.
Which component of the respiratory system help in generation of pressure gradient for breathing? [NCERT Exemplar]
Answer:
The diaphragm and a specialised set of muscles external and internal intercostals between the ribs.

Question 5.
Define Residual Volume (RV). [NCERT Exemplar] Or State the volume of air remaining in the lungs after a normal breathing. [NCERT Exemplar]
Answer:
Residual Volume (RV): It is the volume of air remaining in the lungs even after a forcible expiration. It is about 1100-1200 ml.

Question 6.
What is the RQ for glucose and proteins?
Answer:
Glucose RQ= 1
Proteins RQ = 0.85

Question 7.
Why is it advisable to do nasal breathing rather than mouth breathing?
Answer:
Nasal breathing is advisable because it is healthier as the air inhaled gets filtered in the nose so cleaner air goes to the lungs.

Question 8.
A major percentage of O₂ (97%) is transported by RBCs in the blood. How does the remaining 3% of O₂ transported? [NCERT Exemplar]
Answer:
In dissolved state through plasma.

Question 9.
What is the amount of O₂ supplied to tissues through every 100 mL of oxygenated blood under normal physiological conditions? [NCERT Exemplar]
Answer:
Around. 5 mL.

Question 10.
Cigarette smoking causes emphysema. Give reason. [NCERT Exemplar]
Answer:
Cigarette smoking cause damages to the alveolar walls due to alveolar sacs remaining filled with air leading to decreased respiratory surface for exchange of gases.

Question 11.
What causes snoring?
Answer:
Partial blocking of upper respiratory tract by tongue leading to turbulence of airflow causes a rough rattling inspiratory noise called snoring.

Question 12.
Give the name of some common respiratory disorders.
Answer:
Asthma, emphysema, occupational lung disorders (e.g., Silicosis and asbestosis).

Short answer type questions

Question 1.
Explain the structure of thoracic chamber.
Answer:
Anatomically, thoracic chamber is an air-tight chamber. The thoracic chamber is formed dorsally by the vertebral column, ventrally by the sternum, laterally by the ribs, and on the lower side by the dome-shaped diaphragm. The anatomical setup of lungs in thorax is such that any change in the volume of the thoracic cavity will be reflected in the lung (pulmonary) cavity. Such an arrangement is essential for breathing, as we cannot directly alter the pulmonary volume.

Question 2.
Explain various steps of respiration.
Answer:
Steps of Respiration

• Breathing or pulmonary ventilation by which atmospheric air is drawn in and CO₂-rich alveolar air is released out.
• Diffusion of gases (O₂ and CO₂) across alveolar membrane.
• Transport of gases by the blood.
• Diffusion of O₂ and CO₂ between blood and tissues.
• Utilization of O₂ by the cells for catabolic reactions and resultant release of CO₂.

Question 3.
Give a brief account of exchange of gases during respiration.
Answer:
Alveoli are the primary sites of exchange of gases. Exchange of gases also occur between blood and tissues. O₂ and CO₂ are exchanged in these sites by simple diffusion mainly based on pressure/concentration gradient.
Solubility of the gases as well as the thickness of the membranes involved in diffusion are also some of the important factors that can affect the rate of diffusion. Pressure contributed by an individual gas in a mixture of gases is called partial pressure and is represented as pO₂ for oxygen and pCO₂ for carbon dioxide.

Question 4.
What do you understand by occupational respiratory disorders?
Answer:
In some industries, workers may inhale harmful dust. For example, workers in stone-crushing plant may inhale silica dust. When there is long-term exposure to such situations, lungs can develop inflammation, which leads to fibrosis and ultimately to serious damage to lungs.

Long answer type questions

Question 1.
Explain the mechanism of expiration under normal conditions.
Answer:
Expiration: It is a passive process by which CO₂ is expelled out from the lungs. It takes place when the intra-pulmonary pressure is higher than the atmospheric pressure.
The movement of following muscles are involved :
(a) Diaphragm: The muscle fibres of the diaphragm relax making it convex, decreasing volume of the thoracic cavity.
(b) Internal intercostal muscles: These muscles contract thus, pulling the ribs downward and inward, decreasing the thoracic volume.

The overall volume of the thoracic cavity thus decreases thereby reducing the pulmonary volume.
Ribs and sternum returned to original position (lowered)
As a result, the intrapulmonary pressure increases slightly above the atmospheric pressure. This inturn causes the expulsion of the air from the lungs. The process of expiration is simpler than inspiration.