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Punjab State Board PSEB 11th Class Biology Book Solutions Chapter 16 Digestion and Absorption Textbook Exercise Questions and Answers.

PSEB Solutions for Class 11 Biology Chapter 16 Digestion and Absorption

PSEB 11th Class Biology Guide Digestion and Absorption Textbook Questions and Answers

Question 1.
Choose the correct answer among the following:
(i) Gastric juice contains
(a) pepsin, lipase and rennin
(b) trypsin, lipase and rennin
(c) trypsin, pepsin and lipase
(d) trypsin, pepsin and rennin

(ii) Succus entericus is the name given to
(a) a junction between ileum and large intestine
(b) intestinal juice
(c) swelling in the gut
(d) appendix
Answer:
(i) (a) Pepsin, lipase, and rennin
(ii) (b) Intestinal juice.

Question 2.
Match column I with column II.

Column I	Column II
A. Bilirubin and biliverdin	1. Parotid
B. Hydrolysis of starch	2. Bile
C. Digestion of fat	3. Lipases
D. Salivary gland	4. Amylases

Answer:

Column I	Column II
A. Bilirubin and biliverdin	2. Bile
B. Hydrolysis of starch	4. Amylases
C. Digestion of fat	3. Lipases
D. Salivary gland	1. Parotid

Question 3.
Answer briefly:
(a) Why are villi present in the intestine and not in the stomach?
(b) How does pepsinogen change into its active form?
(c) What are the basic layers of the wall of alimentary canal?
(d) How does bile help in the digestion of fats?
Answer:
(a) The mucosa layer of alimentary canal forms small finger-like foldings called villi in the small intestine. The cells lining the villi produce numerous microscopic projections called microvilli giving a brush border appearance. These modifications increase the surface area enormously.
Villi are supplied with the network of capillaries and large lymph vessel called the lacteal mucosal.

(b) The inactive form of enzyme pepsinogen is activated by Rd.

(c) The wall of alimentary canal from esophagus to rectum possesses four layers namely serosa, muscularis, sub-mucosa and mucosa. Serosa is the outermost layer, followed by muscularis, sub-mucosa and mucosa.

(d) Bile salts help in emulsification of lipids and activate the lipases.

Question 4.
State the role of pancreatic juice in digestion of proteins.
Answer:
The pancreatic juice contains inactive enzymes trypsinogen, chymotrypsinogen, procarboxypeptidases, amylases, lipases, and nucleases. Trypsinogen is aëtivated by an enzyme, enterokinase, secreted by the intestinal mucosa into active trypsin, which in turn activates the other enzymes in the pancreatic juice. Proteins, proteases and peptones (partially hydrolyzed proteins) in the chyme reaching the intestine are acted upon by the proteolytic enzymes of pancreatic juice as given below:

Question 5.
Describe the process of digestion of protein in stomach.
Answer:
The food mixes thoroughly with the acidic gastric juice of the stomach by the churning movements of its muscular wall and is called the chyme. The pepsinogen, on exposure to hydrochloric acid gets converted into the active enzyme pepsin, the proteolytic enzyme of the stomach. Pepsin converts proteins into proteoses and peptones (peptides).

HCl provides the acidic pH (pH 1.8) optimal for pepsins. Rennin is a proteolytic enzyme found in gastric juice of infants which helps in the digestion of milk proteins.

Question 6.
Give the dental formula of human beings.
Answer:
The dental formula of human beings is
\(\frac{2123}{2123} \times 2\).

Question 7.
Bile juice contains no digestive enzymes, yet it is important for digestion. Why?
Answer:
Bile is yellowish-green alkaline solution with 89-98% water, having no digestive enzymes. The bile released into the duodenum contains bile pigments (bilirubin and biliverdin), bile salts, cholesterol, and phospholipids but no enzymes. Bile helps in emulsification of fats, i.e., breaking down of the fats into very small micelles. Bile also activates lipases.

Question 8.
Describe the digestive role of chymotrypsin. Which two other digestive enzymes of the same category are secreted by its source gland?
Answer:
Chymotrypsin is the active form of chymotrypsinogen. It is activated by trypsin. It curdles milk. Nucleases like DNA ase and RNAase and pancreatic lipase are other enzymes secreted by the pancreas.

Question 9.
How are polysaccharides and disaccharides digested?
Answer:
The chemical process of digestion of carbohydrates is initiated in the oral cavity by the hydrolytic action of the carbohydrate splitting enzyme, the salivary amylase. About 30 percent of starch is hydrolyzed here by this enzyme (optimum pH 6.8) into a disaccharide-maltose. Further, carbohydrates in the chyme are hydrolyzed by pancreatic amylase into disaccharides.

Question 10.
What would happen if HCl were not secreted in the stomach?
Answer:
The mucus and bicarbonates present in the gastric juice play an important role in lubrication and protection of the mucosal epithelium from excoriation by the highly concentrated hydrochloric acid.

HCl provides the acidic pH (pH 1.8) optimal for pepsins. Rennin is a proteolytic enzyme found in gastric juice of infants which helps in the digestion of milk proteins. Small amount of lipases are also secreted by gastric glands.

Question 11.
How does butter in your food get digested and absorbed in the body?
Answer:
Bile helps in emulsification of fats, i. e., breaking down of the fats into very small micelles. Bile also activates lipases.

Question 12.
Discuss the main steps in the digestion of proteins as the food passes through different parts of the alimentary canal.
Answer:
Digestion of Protein in Stomach: The proenzyme pepsinogen, on exposure to HCl, gets converted into active enzyme pepsin.

Pepsin always outs in acidic medium (pH 1.8). In infants, main proteins are digested by rennin.

Digestion of Protein in Small Intestine: Pancreatic juice contains proenzyme trypsinogen. It is activated by enterokinase, secreted by intestinal mucosa, into active trypsin. Trypsin acts in alkaline medium.

The dipeptides are changed into amino acids by the enzyme succus enterics (intestinal juice).

Question 13.
Explain the term ‘the codont’ and ‘diphyodont’.
Answer:
Each tooth is embedded in a socket of jaw bone. This type of attachment is called thecodont. The majority of mammals including human beings forms two sets of teeth during their life, a set of temporary milk or deciduous teeth replaced by a set of permanent or adult teeth. This type of dentition is called diphyodont.

Question 14.
Name different types of teeth and their number in an adult human.
Answer:
An adult human has 32 permanent teeth, which are of four different types (heterodont dentition), i.e., incisors (I), canine (C), premolars (Pm), and molars (M), and their number are 4, 2, 4, 6 respectively.

Question 15.
What are the functions of liver?
Answer:
Liver is the largest gland in human body which is mainly responsible for the digestion of food.
Role of liver in digestion of food :

• Its hepatic cells secrete bile juice which passes through the hepatic duct into the gall bladder.
• It has its major role in digestion and processing of proteins.
• Bile secreted by it is mainly responsible for digestion of fats for easy absorption in the body.
• It also responsible for the removal of toxins from blood.

Punjab State Board PSEB 11th Class Biology Book Solutions Chapter 6 Anatomy of Flowering Plants Textbook Exercise Questions and Answers.

PSEB Solutions for Class 11 Biology Chapter 6 Anatomy of Flowering Plants

PSEB 11th Class Biology Guide Anatomy of Flowering Plants Textbook Questions and Answers

Question 1.
State the location and function of different types of meristems.
Answer:
A meristematic tissue represents a group of cells that have retained the power of division throughout the life of an individual. The meristematic tissues are of three types, i.e., apical, intercalary and lateral meristem.

• Apical Meristem: These meristems are present at the apices of shoot and roots of the plants. Apical meristems are responsible for the increase in length of all the primary tissues.
• Intercalary Meristem: It is the meristem that occurs between the mature tissues. They occur in grasses and regenerate parts removed by the grazing herbivores. It contributes to the formation of the primary plant body.
• Lateral Meristem: It occurs in the mature regions of roots arid shoots of many plants, particularly that produce woody axis. These meristems are responsible for producing the secondary tissues.

Question 2.
Cork cambium forms tissues that form the cork. Do you agree with this statement? Explain.
Answer:
Yes, cork cambium forms tissues that form cork. As the stem continues to increase in girth another meristematic tissue called cork cambium or phellogen develops in cortex region of stem. The phellogen cuts off cells on both sides. The outer cells differentiate into cork or phellem. The inner cells differentiate into secondary cortex or phelloderm. Cork is impervious to water due to suberin and provides protection to underlying tissues.

Question 3.
Explain the process of secondary growth in the stems of woody angiosperms with the help of schematic diagrams. What is its significance?
Answer:
Secondary growth in stems of woody angiosperms occur by two types of cambia, i.e., vascular cambium and cork cambium.
(i) Vascular Cambium: Certain cells of medullary rays become meristematic to form interfascicular cambium. The fascicular cambium and the interfascicular cambium join to form a complete ring called cambial ring. The cells of the cambial ring undergo mitotic divisions and produce secondary phloem on its outer side and secondary xylem on its inner side.

At places, vascular cambium possesses ray initials. They form vascular rays, phloem rays in secondary phloem and wood rays in secondary xylem.

As new secondary phloem becomes functional, the previous older phloem gets crushed. Secondary xylem or wood persists. As a result wood grows

with age in the form of annual rings. In each annual ring, there is wide or broader spring or early wood or spring wood and narrow autumn or late wood.

In old stems, the central part of wood becomes non-functional and dark coloured due to tyloses and deposit of resins, gums, tannins. It is called r duramen or heartwood. The outer, functional wood is called sapwood.

(ii) Cork Cambium: As the stem continues to increase in girth due to the activity of vascular cambium the outer cortical and epidermal layers get broken and need to be replaced to provide new protective cell layers. In this way, cork cambium or phellogen develops in the cortex region. Phellogen cuts of cells on both sides.

The outer cells differentiate into cork or phellem while, the inner cells ; differentiate into secondary cortex or phelloderm. Due to the activity of cork cambium, pressure builds up on remaining layers peripheral to
phellogen and ultimately these layers die and slough off. At places, aerating pores called lenticels develop, which have loosely arranged , complementary cells.

Significance of Secondary Growth

• It replaces old non-functional tissues.
• It provides fire proof, insect proof and insulating cover around the older plant parts.
• Commercial cork is a product of secondary growth.
• Wood is the product of secondary growth.

Question 4.
Draw illustrations to bring out the anatomical difference between:
(a) Monocot root and Dicot root
(b) Monocot stem and Dicot stem
Answer:

(a) Anatomical Differences between Monocot Root and Dicot Root
(i) Anatomy of Monocot Root
(a) The structure of epidermis, cortex, endodermis and pericycle of a monocot root resembles exactly those of a dicot root.
(b) Vascular bundles are radial, and polyarch.
(c) Pith is large and well-developed; it is composed of parenchyma cells

(ii) Anatomy of dicot root

T.S of Dicot root
(a) Epidermis is single layered and many cells bear root hairs; cuticle is absent.
(b) Cortex is made of several layers of parenchyma cells.
(c) Endodermis consists of a single-layer of cells. The cells have a deposition of suberin, in the form of casparian strips, on their radial and tangential walls.
(d) Pericycle comprises a few layers of specialised parenchyma cells inner to the endodermis.
(e) Vascular bundles are radial and may range between two and six, though commonly there are four groups; i.e., tetrarch; xylem is exarch.
(f) Pith is very small and made of parenchyma cells.

(b) Anatomical Differences between Monocot Stem and Dicot stem
(i) Anatomy of monocot stem
(a) Epidermis is single layered and trichomes are absent; cuticle is present on its outer surface.
(b) Hypodermis consists of two or three layers of sclerenchyma cells.
(c) Ground tissue is parenchymatous and is not differentiated into cortex or pith.
(d) Vascular bundles are many and scattered in the ground tissue; they vary in size.

T.S. of Monocot Stem

• Each vascular bundle is surrounded by sclerenchymatous bundle sheath.
• The vascular bundles are conjoint and closed; xylem is endarch and characteristically a protoxylem lacuna is present.

(ii) Anatomy of dicot stem
(a) Epidermis is the outermost layer of cells; externally it is covered with a cuticle and may bear trichomes and a few stomata.
(b) Hypodermis consists of a few layers of collenchyma cells, just below the epidermis.
(c) Cortex consists of parenchyma cells.
(d) Endodermis is single layered and the cells are rich in starch grains and hence it is also referred to as starch sheath.
(e) Pericyde occurs inner to the endodermis, above the phloem of vascular bundles in the form of semi-lunar patches (hence also referred to as bundle caps); it is composed of sclerenchyma.
T.S. of Dicot Stem

(f) Vascular bundles are characteristically arranged in the form of a ring.

• Each vascular bundle is conjoint and open with intra-fascicular cambium; xylem is endarch.
  (g) Medullary rays are the few layers of radially placed parenchyma cells, in between the vascular bundles.
  (h) Pith is composed of parenchyma cells.

Question 5.
Cut a transverse section of young stem of a plant from your school garden and observe it under the microscope. How would you ascertain whether it is a monocot stem or a dicot stem? Give reasons.
Answer:
Transverse section of a monocot stem possess following characters:

• Dumbbell-shaped guard cells in stomata in epidermis.
• Sclerenchymatous hypodermis.
• No concentric arrangement of internal tissues.
• Unifrom ground tissue showing no tissue differentiation.
• More than 8 scattered vascular bundles.
• Bundle sheath is present.
• No secondary growth normally.
• Xylem vessels arranged in Y-shaped manner.
• Protoxylem cavity usually present in vascular tissues.

Transverse section of a dicot stem possess following characters:

• Kidney-shaped guard cells in stomata present in epidermis.
• Collenchymatous hypodermis.
• Concentric arrangement of internal tissues.
• Differentiation of ground tissue into cortex, endodermis, pericycle and pith.
• The vascular bundles are arranged in a ring.
• Conjoint, collateral and open vascular bundles.
• Without bundle sheath.
• Secondary growth takes place.
• Xylem vessels arranged in rows.

[Note: For figures refer to Q.No. 4]

Question 6.
The transverse section of a plant material shows the following anatomical features:
(a) The vascular bundles are conjoint, scattered and surrounded by a sclerenchymatous bundle sheaths.
(b) Phloem parenchyma is absent. What will you identify it as?
Answer:
It is a transverse section of monocotyledonous stem.

Question 7.
Why are xylem and phloem called complex tissues?
Answer:
Xylem and phloem are made up of more than one type of cells that is why they are called as complex tissues :
(i) Xylem is composed of four different kinds of elements, namely-tracheids, vessels, xylem fibres and xylem parenchyma. Tracheids are dead tube-like cells which are thick walled, vessels are made up of large number of tube cells placed end to end. Xylem fibres are thick walled cells that maybe septate and aseptate. Xylem parenchyma is living and thin walled cells.

(ii) Phloem is composed of sieve tube elements, companion cells, phloem parenchyma and phloem fibres. Sieve tube elements are tube-like cells, whereas phloem parenchyma are living cells and phloem fibres are thick walled lignified cells.

Question 8.
What is stomatal apparatus? Explain the structure of stomata with a labelled diagram.
Answer:
The minute pores present in the epidermis are known as stomata. The stomata may be surrounded by either bean-shaped (in dicots) or by dumb-bell-shaped (in monocots) guard cells. The guard cells in turn are surrounded by other epidermal cells, which are known as subsidiary or

accessory cells. The stomatal aperture, guard cells, accessory cells constitute the stomatal apparatus.

Question 9.
Name the three basic tissue systems in the flowering plants. Give the tissue names under each system.
Answer:
The three basic; tissue systems in flowering plants are as follows:

• Epidermal Tissue System: The tissue related to this system are epidermis, cuticle and wax, stomata and trichomes.
• Ground Tissue System: It consists of cortex, endodermis, pericycle, medullary rays, pith and ground tissue of leaves.
• Vascular Tissue System: It contains conducting tissues like xylem and phloem.

Question 10.
How is the study of plant anatomy useful to us?
Answer:
Plant anatomy is the study of internal structure of living organisms.

• It describes the tissues involved in assimilation of food and its storage, transportation of water, i.e., xylem tissue, transportation of minerals. i.e., phloem and those involved in providing mechanical support to the plant,
• Study of internal structure of plants helps to understand their adaptations of diverse environments.
• The study of plant anatomy also help in understanding the functional organisation of higher plants.

Question 11.
What is periderm? How does periderm formation take place in
the dicot stems?
Answer:
Phellogen, phellem and phelloderm are collectively called as periderm. Phellogen develops usually in the cortex region. Phellogen is a couple of layers thick. Phellogen cuts off cells on both sides. The outer cells 1 differentiate into cork or phellem, while the inner cells differentiate into secondary cortex or phelloderm. All these together form periderm.

Question 12.
Describe the internal structure of a dorsiventral leaf with the help of labelled diagrams.
Answer:
The vertical section of a dorsiventral leaf through the lamina shows three ; main parts namely, epidermis, mesophyll and vascular system. The epidermis which covers both the upper surface (adaxial epidermis) and lower surface (abaxial epidermis) of the leaf has a conspicuous cuticle. The abaxial epidermis generally bears more stomata than the adaxial epidermis. The latter may even lack stomata. The tissue between the upper and the lower epidermis is called the mesophyll. Mesophyll, which possesses chloroplasts and carry out photosynthesis, is made up of parenchyma. It has two types of cells – the palisade parenchyma and the spongy parenchyma.

The adaxially placed palisade parenchyma is made up of elongated cells, which are arranged vertically and parallel to each other. The oval or round and loosely arranged spongy parenchyma is situated below the palisade cells and extends to the lower epidermis. There are numerous large spaces and air cavities between these cells. Vascular system includes vascular bundles, which can be seen in the veins and the midrib. The size of the vascular bundles are dependent on the size of the veins. The veins vary in thickness in the reticulate venation of the dicot leaves. The vascular bundles are surrounded by a layer of thick walled bundle sheath cells.
T.S. of Dorsiventral Leaf

Punjab State Board PSEB 11th Class Biology Book Solutions Chapter 17 Breathing and Exchange of Gases Textbook Exercise Questions and Answers.

PSEB Solutions for Class 11 Biology Chapter 17 Breathing and Exchange of Gases

PSEB 11th Class Biology Guide Breathing and Exchange of Gases Textbook Questions and Answers

Question 1.
Define vital capacity. What is its significance?
Answer:
Vital Capacity (VC): The maximum volume of air a person can breathe in after a forced expiration is called vital capacity. Vital capacity is higher in athletes and singers. Vital capacity shows the strength of our inspiration and expiration.

Question 2.
State the volume of air remaining in the lungs after a normal breathing.
Answer:
The volume of air remaining in the lungs even after a forcible expiration averages 1100 ml to 1200 ml.

Question 3.
Diffusion of gases occurs in the alveolar region only and not in the other parts of respiratory system. Why?
Answer:
Alveoli are the primaty sites of gas exchange in the respiratory system. Exchange of gases occur between blood and these tissues. O₂ and CO₂ are exchanged in these sites by simple diffusion mainly based on pressure/concentration gradient. The diffusion membrane for gas exchange is made up of three major layers.
These layers are :

1. Squamous epithelium of alveoli.
2. Endothelium of alveolar capillaries.
3. Basement substance in between them. Its total thickness is much less than a millimetre. Therefore, all the factors in our body are favourable for diffusion of O₂ from alveoli to tissues and that of CO₂ from tissues to alveoli.

Question 4.
What are the major transport mechanisms for CO₂? Explain.
Answer:
Transport of Carbon Dioxide: CO₂ in gaseous form diffuses out of the cells into capillaries, where it is transported in following ways :
(i) Transport in dissolved form: About 7% CO₂ is carried in dissolved form through the plasma because of its high solubility.
(ii) Transport as bicarbonate: The largest fraction (about 70%) is carried in plasma as bicarbonate ions (HCO₃). At the tissues site, where pCO₂ is high due to catabolism, CO₂ diffuses into the blood (RBCs and plasma) and forms HCO₃^– and H^–.

This reaction is faster in RBCs because they contain an enzyme carbonic anhydrase. Hydrogen ion released during the reaction bind to Hb, triggering the Bohr effect.
At the alveolar site, where pCO₂ is low, the reaction proceeds in opposite direction forming CO₂ and H₂O. Thus, CO₂ trapped as bicarbonate at tissue level and transported to alveoli is released as CO₂.

(iii) Transport as carbaminohaemoglobin: Nearly 20-25% CO₂ is carried by haemoglobin as carbaminohaemoglobin, CO₂ entering the blood combines with the NH₂ group of the reduced Hb.

The reaction releases oxygen from oxyhaemoglobin.
Factors affecting the binding of CO₂ and Hb are as follows:

• Partial pressure of CO₂.
• Partial pressure of O₂ (major factor).

In tissues, pCO₂ is high and pO₂ is low, more binding of CO₂ occurs while, in the alveoli, pCO₂ is low and pO₂ is high, dissociation of CO₂ from HbCO₂ takes place, i.e., CO₂, which is bound to Hb from the tissues is delivered at the alveoli.

Question 5.
What will be the pO₂ and pCO₂, in the atmospheric air compared to those in the alveolar air?
(i) pO₂ lesser and pCO₂ higher
(ii) pO₂ higher and pCO₂ lesser
(iii) pO₂ higher and pCO₂ higher
(iv) pO₂ lesser and pCO₂ lesser
Answer:
(i) In the alveolar tissues, where low pO₂, high pCO₂, high H⁺ concentration, these conditions are favourable for dissociation of oxygen from the oxyhaemoglobin.

(ii) When there is high pO₂, low pCO₂, less H⁺ concentration and lesser temperature, the factors are all favourable for formation of oxyhaemoglobin.

(iii) When pO₂ is high in the alveoli and pCO₂ is high in the tissues then the oxygen diffuses into the blood and combines with oxygen forming oxyhaemoglobin and CO₂ diffuses out.

(iv) When pO₂ is low in the alveoli and pCO₂ is low in the tissues then these conditions are favourable for dissociation of oxygen from the oxyhaemoglobin.

Question 6.
Explain the process of inspiration under normal conditions.
Answer:
Inspiration is the process during which atmospheric air is drawn in. Inspiration is initiated by the contraction of diaphragm, which increases the volume of thoracic chamber in the anteroposterior axis. The contraction of external intercostal muscles lifts up the ribs and the sternum causing an increase in the volume of the thoracic chamber in the dorso-ventral axis.

The overall increase in the thoracic volume causes a similar increase in pulmonary volume. An increase in pulmonary volume decreases the intrapulmonary pressure to less than the atmospheric pressure, which forces the air from outside to move into the lungs, i. e., inspiration. On an average, a healthy human breathes 12-16 times/minute.

Question 7.
How is respiration regulated?
Answer:
Respiratory rhythm centre is primarily responsible for regulation of respiration. This centre is present in the medulla.
Pneumotaxic centre, present in the pons region, also coordinates respiration. Apart from them, receptors associated with aortic arch and carotid artery, can also recognize changes in CO₂ and H⁺ concentration and send signal to the rhythm centre for proper action.

Question 8.
What is the effect of pCO₂ on oxygen transport?
Answer:
Partial pressure of CO₂ (pCO₂) can interfere the binding of oxygen with haemoglobin, i.e., to form oxyhaemoglobin.
(i) In the alveoli, where there is high pO₂ and low pCO₂, less H⁺ concentration and low temperature, more formation of oxyhaemoglobin occur.

(ii) In the tissues, where low pO₂, high pCO₂, high H⁺ concentration and high temperature exist, the conditions are responsible for dissociation of oxygen from the oxyhaemoglobin.

Question 9.
What happens to the respiratory process in a man going up a hill?
Answer:
At hills, the pressure of air falls and the person cannot get enough oxygen in the lungs for diffusion in blood. Due to deficiency of oxygen, the person feels breathlessness, headache, dizziness, nausea, mental fatigue and a bluish colour on the skin, nails and lips.

Question 10.
What is the site of gaseous exchange in an insect?
Answer:
The actual site of gaseous exchange in an insect is tracheoles and tracheolar end cells.

Question 11.
Define oxygen dissociation curve. Can you suggest any reason for its sigmoidal pattern?
Answer:
A sigmoid curve is obtained when percentage saturation of haemoglobin with O₂ is plotted against the pO₂.
This curve is called the oxygen dissociation curve and is highly useful in studying the effect of factors like pCO₂, H⁺ concentration, etc., on binding of O₂ with haemoglobin.

In the alveoli, where there is high pO₂, low pCO₂, lesser H⁺ concentration and lower temperature, the factors are all favourable for the formation of oxyhaemoglobin, whereas in the tissues, where low pO₂, high pCO₂, high H⁺ concentration and higher temperature exist, the conditions are favourable for dissociation of oxygen from the oxyhaemoglobin. This dearly indicates that O₂ gets bound to haemoglobin in the lung surface and gets dissociated at the tissues. Every 100 ml of oxygenated blood can deliver around 5 ml of O₂ to the tissues under normal physiological conditions.

Question 12.
Have you heard about hypoxia? Try to gather information about it, and discuss with your friends.
Answer:
Hypoxia is the shortage of oxygen supply to the blood due to :
(a) normal shortage in air
(b) oxygen deficiency on high mountains (mountain sickness), anaemia and phytotoxicity or poisoning of electron transport system.

Question 13.
Distinguish between:
(a) IRV and ERV
(b) Inspiratory Capacity and Expiratory Capacity
(c) Vital Capacity and Total Lung Capacity
Answer:
(a) IRV and ERV Inspiratory Reserve Volume (IRV): Additional volume of air, a person can inspire by a forcible inspiration. This is about 2500-3000 mL. Expiratory Reserve Volume (ERV): Additional volume of air, a person can expire by a forcible expiration. This is about 1000-1100 mL.

(b) Inspiratory Capacity and Expiratory Capacity Inspiratory Capacity (IC): Total volume of air a person can inspire after a normal expiration. This includes tidal volume and inspiratory reserve volume (TV+IRV).
Expiratory Capacity (EC): Total volume of air a person can expire after a normal inspiration. This includes tidal volume and expiratory reserve volume (TV+ERV)

(c) Vital Capacity and Total Lung Capacity
Vital Capacity (VC): The maximum volume of air, a person can breathe in after a forced expiration. This includes ERV, TV and IRV or the maximum volume of air a person can breathe out after a forced inspiration.
Total Lung Capacity (TLC): Total volume of air accommodated in the lungs at the end of a forced inspiration. This includes RV, ERV, TV and IRV or vital capacity + residual volume.

Question 14.
What is tidal volume? Find out the tidal volume (approximate value) for a healthy human in an hour.
Answer:
Tidal Volume (TV): Volume of air inspired or expired during a normal respiration is called tidal volume. It is about 500 mL., i.e., a healthy man can inspire or expire approximately 6000 to 8000 mL of air per minute.

Punjab State Board PSEB 11th Class Biology Book Solutions Chapter 18 Body Fluids and Circulation Textbook Exercise Questions and Answers.

PSEB Solutions for Class 11 Biology Chapter 18 Body Fluids and Circulation

PSEB 11th Class Biology Guide Body Fluids and Circulation Textbook Questions and Answers

Question 1.
Name the components of the formed elements in the blood and mention one major function of each of them.
Answer:
(a) Erythrocytes: They are also known as Red Blood Cells (RBC). They are the most abundant of all the cells in blood. A healthy’adult man has, on an average, 5 millions to 5.5 millions of RBCs mm ^-3 of blood. RBCs are formed in the red bone marrow in the adults.
RBCs are devoid of nucleus in most of the mammals and are biconcave in shape. They have a red coloured, iron containing complex protein called haemoglobin. A healthy individual has 12-16 gms of haemoglobin in every 100 ml of blood.
these molecules play a significant role in transport of respiratory gases. RBCs have an average life span of 120 days after which they are destroyed in the spleen. Hence, spleen is also known as the graveyard of RBCs.

(b) Leucocytes: They are also known as White Blood Cells (WBC) as they are colourless due to the lack of haemoglobin. They are nucleated and are relatively lesser in number which averages 6000-8000 mm^-3 of blood. Leucocytes are generally short-lived.

There are two main categories of WBCs :
1. Granulocytes, e.g., neutrophils, eosinophils and basophils
2. Agranulocytes. e.g., lymphocytes and monocytes.
Neutrophils are the most abundant cells (60-65 per cent) of the total WBCs and basophils are the least (0.5-1 per cent) among them. Neutrophils and monocytes (6-8 per cent) are phagocytic cells which destroy foreign organisms entering the body.

Basophils secrete histamine, serotonin, heparin, etc., and are involved in inflammatory reactions. Eosinophils (2-3 per cent) resist infections and are also associated with allergic reactions. Lymphocytes (20-25 per cent) are of two major types- ‘B’ and T forms. Both B and T lymphocytes are responsible for immune responses of the body.

(c) Platelets: Platelets or thrombocytes, are involved in the coagulation or clotting of blood. A reduction in their number can lead to clotting disorders, which will lead to excessive loss of blood from the body.

Question 2.
What is the importance of plasma proteins?
Answer:
Fibrinogen, globulins and albumins are the major plasma proteins. Fibrinogens are needed for clotting or coagulation of blood. Globulins primarily are involved in defense mechanisms of the body and the albumins help in osmotic balance.

Question 3.
Match column I with column II.

Column I	Column II
A. Eosinophils	1. Coagulation
B. RBC	2. Universal recipient
C. AB group	3. Resist infections
D. Platelets	4. Contraction of heart
E. Systole	5. Gas transport

Answer:

Column I	Column II
A. Eosinophils	3. Resist infections
B. RBC	5. Gas transport
C. AB group	2. Universal recipient
D. Platelets	1. Coagulation
E. Systole	4. Contraction of heart

Question 4.
Why do we consider blood as a connective tissue?
Answer:
Blood is a mobile connective tissue derived from mesoderm which consists of fibre-free fluid matrix, plasma and other cells. It regularly circulates in the body, takes part in the transport of materials.

Question 5.
What is the difference between blood and lymph?
Answer:
Differences between Blood and Lymph

Blood	Lymph
It is red in colour due to the presence of haemoglobin in red cells.	It is colourless as red blood cells are absent.
It consists of plasma, RBC, WBC and platelets.	It consists of plasma and less number of WBC.
Glucose concentration is low.	Glucose concentration is higher than blood.
Clotting of blood is a fast process.	Clotting of lymph is comparatively slow.
It transports materials from one organ to other.	It transports materials from tissue cells into the blood.
Flow of blood is fast.	Lymph flows very slowly.
Its plasma has more proteins, calcium and phosphorus.	Its plasma has less protein, calcium and phosphorus.
It moves away from the heart and towards the heart.	It moves in one direction, i. e., from tissues to sub-clavians.

Question 6.
What is meant by double circulation? What is its significance?
Answer:
Double Circulation: In double circulation, the blood passes twice through the heart during one complete cycle. Double circulation is carried out by two ways :
1. Pulmonary circulation,
2. Systemic circulation

Significance: In birds and mammals, oxygenated and deoxygenated blood received by the left and right atria respectively passes on to the ventricles of the same sides. The ventricles pump it out without mixing up, i.e., two separate circulatory pathways are present in these organisms. This is the importance of double circulation.

Question 7.
Write the differences between:
(a) Blood and lymph
(b) Open and closed system of circulation
(c) Systole and diastole
(d) P-wave and T-wave
Answer:
(a)

Blood	Lymph
It is red in colour due to the presence of haemoglobin in red cells.	It is colourless as red blood cells are absent.
It consists of plasma, RBC, WBC and platelets.	It consists of plasma and less number of WBC.
Glucose concentration is low.	Glucose concentration is higher than blood.
Clotting of blood is a fast process.	Clotting of lymph is comparatively slow.
It transports materials from one organ to other.	It transports materials from tissue cells into the blood.
Flow of blood is fast.	Lymph flows very slowly.
Its plasma has more proteins, calcium and phosphorus.	Its plasma has less protein, calcium and phosphorus.
It moves away from the heart and towards the heart.	It moves in one direction, i. e., from tissues to sub-clavians.

(b) Differences between Open and Closed Circulatory Systems

Open Circulatory System	Closed Circulatory System
1. It is present in arthropods and molluscs.	It is present in annelids and chordates.
2. Blood pumped by heart passes through large vessels into open spaces or body cavities called sinuses.	Blood pumped by the heart is circulated through a loosed network of blood vessels.
3. Flow of blood is not regulated precisely.	It is more advantageous as the blood flow is more precisely regulated.

(c) Differences between Systole and Diastole

Systole	Diastole
1. The contraction of the muscles of auricles and ventricles is called systole.	It is the relaxation of atria and ventricle muscle.
2. It increases the ventricular pressure causing the closure of tricuspid and bicuspid valves due to attempted backflow of blood into atria.	The ventricular pressure falls causing the closure of semilunar valves which prevent backflow of blood into the ventricle.
3. Systolic pressure is higher and occurs during ventricular contraction.	Diastolic pressure is lower and occurs during ventricular expansion.

(d) Differences between P-wave and T-wave

P-wave	T-wave
The P-wave represents the electrical excitation (or depolarisation) of the arrÍa, which leads to the contraction of both the arria.	The T-wave represents the return of the ventricles from excited to normal state (repolarisation). The end of the T-wave marks the end of systole.

Question 8.
Describe the evolutionary change in the pattern of heart among the vertebrates.
Answer:
The heart among the vertebrates shows different patterns of evolution. Different groups of animals have evolved different methods for this transport. All vertebrates possess a muscular chambered heart.
Fishes have a 2-chambered heart with an atrium and a ventricle.
Amphibians and the reptiles (except crocodiles) have a 3-chambered heart with two atria and a single ventricle.
In crocodiles, birds and mammals possess a 4-chambered heart with two atria and two ventricles.

In fishes, the heart pumps out deoxygenated blood which is oxygenated by the gills and supplied to the body parts from where deoxygenated blood is returned to the heart.

In amphibians and reptiles, the left atrium receives oxygenated blood from the gills/lungs/skin and the right atrium gets the deoxygenated blood from other body parts. However, they get mixed up in the single ventricle which pumps out mixed blood.

In birds and mammals, oxygenated and deoxygenated blood received by the left and right atria respectively passes on to the ventricles of the same sides. The ventricles pump it out without any mixing up, i. e., two separate circulatory pathways are present in these organisms, hence, these animals have double circulation.

Question 9.
Why do we call our heart myogenic?
Answer:
Heart is myogenic in origin because the cardiac impulse is initiated in our heart muscles.

Question 10.
The sino-atrial node is called the pacemaker of our heart. Why?
Answer:
The sino-atrial node of heart is responsible for initiating and maintaining the rhythmic activity, therefore it is known as pacemaker of the heart.

Question 11.
What is the significance of atrioventricular node and atrioventricular bundle in the functioning of heart?
Answer:
Atrioventricular Node (AVN): It is the mass of tissue present in the lower-left corner of the right atrium close to the atrioventricular septum. It is stimulated by the impulses that sweep over the atrial myocardium. It is too capable of initiating impulses that cause contraction but at slower rate than SA node.

Atrioventricular Bundle (AV Bundle): It is a bundle of nodal fibres, which continues from AVN and passes through the atria-ventricular septa to emerge on the top of interventricular septum. The AV bundle, bundle branches and Purkinje fibres convey impulses of contraction from the AV node to the apex of the myocardium. Here the wave of ventricular contraction begins, then sweeps upwards and outwards, pumping blood into the pulmonary artery and the aorta.
This nodal musculature has the ability to generate action potentials without any external stimuli.

Question 12.
Define a cardiac cycle and the cardiac output.
Answer:
Cardiac Cycle: The sequential event in the heart which is cyclically repeated is called the cardiac cycle. It consists of systole and diastole of both the atria and ventricles.

Cardiac Output: It is the volume of blood pumped out by each ventricle per minute and averages 5000 mL or 5 L in a healthy individual. The body has the ability to alter the stroke volume as well as the heart rate and thereby the cardiac output. For example, the cardiac output of an athlete will be much higher than that of an ordinary man.

Question 13.
Explain heart sounds.
Answer:
During each cardiac cycle, two prominent sounds are produced which can be easily heard through a stethoscope. The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves, whereas the second heart sound (dup) is associated with the closure of the semilunar valves. These sounds are of clinical diagnostic significance.

Question 14.
Draw a standard ECG and explain the different segments in it.
Answer:
Electrocardiograph (ECG): ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle. A patient is connected to the machine with three electrical leads (one to each wrist and to the left ankle) that continuously monitor the heart activity. For a detailed evaluation of the heart’s function, multiple leads are attached to the chest region.

Each peak in, the ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart. The P-wave represents the electrical excitation (or depolarization) of the atria, which leads to the contraction of both the atria. The QRS complex represents the depolarization of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole.

• The T-wave represents the return of the ventricles from excited to normal state (repolarisation).
• The end of the T-wave marks the end of systole.
• Obviously, by counting the number of QRS complexes that occur in a given time period, one can determine the heartbeat rate of an individual.
• Since the ECGs obtained from different individuals have roughly the same shape for a given lead configuration, any deviation from this shape indicates a possible abnormality or disease.
• Hence, it is of a great clinical significance.

Punjab State Board PSEB 11th Class Biology Book Solutions Morphology of Flowering Plants Textbook Exercise Questions and Answers.

PSEB Solutions for Class 11 Biology Morphology of Flowering Plants

PSEB 11th Class Biology Guide Morphology of Flowering Plants Textbook Questions and Answers

Question 1.
What is meant by modification of root? What type of modification of root is found in the:
(a) Banyan tree
(b) Turnip
(c) Mangrove trees
Answer:
Modification of Root: Roots in some plants change their shape and
structure and become modified to perform functions, other than absorption and conduction of water and minerals. The roots are modified for water, absorption, support, storage of food and respiration.
(a) A banyan tree have hanging roots known as prop roots.
(b) The roots of turnip get modified to become swollen and store food.
(c) The roots of mangrove trees get modified to grow vertically upwards and help to get oxygen for respiration. These are known as pneumatophores.

Question 2.
Justify the following statements on the basis of external features:
(a) Underground parts of a plant are not always roots.
(b) Flower is a modified shoot.
Answer:
(a) Underground parts of a plant are not always roots, they are subterranean stems which do not have root hairs and root cap. Have terminal bud, nodes and internodes. Have leaves on the nodes.
Most of the underground stems such as sucker, rhizome, corm, tubers, bulb, etc., store food, form aerial shoots.
(b) Flower is a modified shoot because:

• It possess nodes and internodes.
• It may develop in the axil of small leaf-like structure called bract.
• Flowers get modified into bulbils or fleshy buds in some plants.
• Anatomically the pedicel and thalamus of a flower resemble that of stem.
• The vascular supply of different organs of flower resemble that of normal leaves.
• In the flower of Degeneria, the stamens are expanded like leaves and the carpels appear like folded leaves.

Question 3.
How is a pinnately compound leaf different from a palmately compound leaf?
Answer:
In pinnately compound leaf, the number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf as in neem. In case of a palmately compound leaf, the leaflets are attached at a common point, i e., at the tip of petiole as in silk cotton.

Question 4.
Explain with suitable examples the different types of phyllotaxy.
Answer:
Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. This is usually of three types—alternate, opposite and whorled.

• In alternate phyllotaxy, a single leaf arises at each node in alternate manner, as in China rose, mustard and sunflower plants.
• In opposite type of phyllotaxy, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants.
• If more than two leaves arise at each node and form, a whorl, it is called as whorled, as in Alstonia.

Question 5.
Define the following terms:
(i) Aestivation
(ii) Placentation
(iii) Actinomorphic
(iv) Zygomorphic
(v) Superior ovary
(vi) Perigynous flower
(vii) Epipetalous stamen
Answer:
(i) Aestivation: The mode of arrangement of sepals or petals in relation to one another in a flower bud is called aestivation.
(ii) Placentation: The pattern by which the ovules are attached in an ovary is called placentation.

(iii) Actinomorphic: A flower having radial symmetry. The parts of each whorl are similar in size and shape. The flower can be divided in two equal halves along more than one median longitudinal plane.

(iv) Zygomorphic: A flower having bilateral symmetry. The parts of one or more whorls are dissimilar. The flower can be divided into two equal halves in only one vertical plane.

(v) Superior ovary: The ovary is called superior when it is borne above the point attachment of perianth and stamens on the thalamus.

(vi) Perigynous flower: It is the condition in which gynoecium of a flower is situated in the centre and other parts of the flower are located on the rim of the thalamus almost at the same level.

(vii) Epipetalous stamen: Stamens adhere to the petals by their filaments so, appear to arise from them.

Question 6.
Differentiate between:
(a) Racemose and cymose inflorescence
(b) Fibrous root and adventitious root
(c) Apocarpous and syncarpous ovary
Answer:
(a) Differences between Racemose and Cymose Inflorescence.

Racemose	Cymose
1. This is further divided into (a) Raceme (b) Catkin (c) Spike (d) Spadix (e) Corymb (f) Umbel or capitutum	It is further divided into (a) Monochasial cyme (b) Dichasial Cyme (c) Polychasial Cyme.
2. Branches develop indefinitely and further branches arise laterally in acropetal manner.	The branches arise from terminal buds and stop growing after some time Lateral branches grow much vigorously and spread like a dome.

(b) Differences between Fibrous Root and Adventitious Root

Fibrous Root	Adventitious Root
In monocotyledonous plants, the primary root is short lived and is replaced by a latge number of roots. These roots originate from the base of the fibrous root system say, for example in wheat plants.	In some plants, say for example, in grass and banyan tree there are roots arising from parts of the plant other than the radicle. These are called adventitious roots.

(c) Differences between Apocarpous Ovaiy and Syncarpous Ovary

Apocarpous Ovary	Syncarpous Ovary
When more than one carpel is present, they may be free (as in lotus and rose) and are called apocarpous ovary.	They are termed syncarpous ovary when fused, as in mustard and tomato. After fertilisation, the ovules develop into seeds and like ovary matures into a fruit.

Question 7.
Draw the labelled diagram of the following:
(a) gram seed
(b) V.S. of maize seed
Answer:
(a) Gram Seed

(b) V.S. of maize seed

Question 8.
Describe modifications of stem with suitable examples. [NCERT]
Answer:
Modifications of stem are as follows:

• Tendrils help plants to climb on the support, e. g., Cucumber.
• Thorns are woody, pointed, straight structures to protect plants from browsing animals, e. g., Bougainvillea.
• The plants in arid regions modify their stems into flattened (Opuntia) or fleshy cylindrical (Euphorbia) structures. They contain chlorophyll and carry out photosynthesis.
• Underground stems of some plants such as grass and snawberry, etc., spread to new riches and when older parts die, new plants are formed.
• In Pistia and Eichhornia, a lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots is found.
• Stolons or runners help in vegetative propagation in jasmine and grass, respectively.

Question 9.
Take one flower each of the families Fabaceae and Solanaceae and write its semi-technical description. Also draw their floral diagram after studying them.
Answer:
(i) Fabaceae: This family was earlier called Papilionoideae, a subfamily of family Leguminosae.
(a) Habit: Trees, shrubs, herbs, climbers, etc.
(b) Root System: Tap root system with root nodules, that harbour nitrogen fixing bacterium.
(c) Leaves: Leaves are alternate, simple or pinnately compound, pulvinate, and stipulate; venation reticulate.
(d) Inflorescence: Racemose usually, a raceme.
(e) Flowers: Bracteate, bracteolate, bisexual, zygomorphic, hypogynous, and pentamerous.
(f) Calyx: Five sepals, gamosepalous, irregular, odd sepal anterior (characteristic feature of the family) and valvate aestivation.

(g) Corolla: Corolla consists of five petals, polypetalous, characteristically papilionaceous, with an odd posterior large petal called standard or vexillum, a pair of lateral petals, called wing or alae and two anterior keel or carina, which enclose the essential organs; aestivation is vexillary.
(h) Androecium: Ten stamens, diadelphous, [(9) + 1] and anthers dithecous.
(i) Gynoecium: Ovary is superior, monocarpellary, unilocular with many ovules on marginal placenta; style single, curved or bent at right angles to the ovary.
(j) Fruits and Seeds: Characteristically a legume/pod and seeds are non-endospermic.
(k) Floral Formula:
(l) Economic Importance: Plants of this family yield pulses, edible oil, dye, fodder, fibres and wood; some yield products of medicinal value,

(ii) Solanaceae (Potato family)
(a) Habit: Plants are mostly herbs or shrubs or small trees; stem is erect, cylindrical, branched (cymose type); stem is underground in potato CSolarium tuberosum).
(b) Leaves: Simple, alternate, exstipulate with reticulate venation.
(c) Inflorescence: Axillary or extra-axillary cymose, or solitary.
(d) Flowers: Bisexual, actinomorphic, hypogynous and pentamerous.
(e) Calyx: Five sepals, gamosepalous, persistant and valvate aestivation.
(f) Corolla: Five petals, gamopetalous, valvate or imbricate, rotate/wheel-shaped.
(g) Androecium: Five stamens, epipetalous and alternating with the petals.
(h) Gynoecium: Bicarpellary, syncarpous, superior with many ovules on swollen axile placenta; carpels are obliquely placed.
(i) Fruits and Seeds: A berry (tomato and brinjal) or a capsule; seeds are endospermic.
(j) Floral Formula :
(k) Economic Importance: Many plants are used as source of food (vegetables), spice, medicines of fumigatory; some are ornamental plants.

Question 10.
Describe the various types of placentations found in flowering plants.
Answer:
Types of Placentations: The arrangement of ovules within the ovary is known as placentation. The placentations are of different types – marginal, axile, parietal, free central and basal.

Marginal placentation: In this placentation, the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows as in pea.

Axile placentation: In this placentation, the placenta is axile and the ovules are attached to it in a multilocular ovary as in China rose, tomato, etc.

Parietal placentation: In this placentation, the ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one chambered but it becomes two chambered due to the formation of a false septum known as replam, e.g., mustard.

Free central placentation: In this type of placentation, the ovules are present on the central axis of ovary and septa are absent as in Dianthus and primrose.

Basal placentation: In this placentation the placenta develops at the base of ovary and a single ovule is attached to it, as in sunflower.

Question 11.
What is a flower? Describe the parts of a typical angiospermic flower.
Answer:
Flower: It is a condensed modified reproductive shoot found in angiosperms. It often develops in the axile of a small leaf-like structure called bract. The stalk of the flower is called pedicel. The tip of the pedicel or the base of flower has a broad highly condensed multinodal region called thalamus.
A flower has following four floral structures:

• Calyx: It is made up of sepals. These are green in colour and help in photosynthesis.
• Corolla: It is the brightly coloured part containing petals.
• Androecium: It is the male reproductive part which consists of stamens. A stamen has a long filament and terminal anther. The anther produces the pollen grains.
• Gynoecium: It is the female reproductive part which consists of
  carpels. A carpel has three parts, i.e., style, stigma and ovary. The ovary bears the ovules.

Question 12.
How do the various leaf modifications help plants?
Answer:
Leaf Modifications in Plants
(i) In some plants, the leaf and leaf parts get modified to form green, long, thin unbranched and sensitive thread-like structures called tendrils. The tendrils coil around the plant and provide support to the plant in climbing. Tendrils are present in pea, garden Nasturtium, Clematis, Smilax, etc.

(ii) In some plants, the leaves get modified to form curved stiff claw like hooks to help the plant in clinging to the support. Leaflet hooks are present in Bignonia.

(iii) In case of Acacia and Zizyphus, the leaves get modified to form vasculated, hard, stiff and pointed structures.

(iv) In case of Acacia longifolia, the expanded petiole gets modified and perform the function of photosynthesis in absence of lamina.

(v) In plants such as Nepenthes, the lamina is modified to form large pitcher. It is used for storing water and for digesting insect protein.

(vi) In case of Utricularia, the leaf segments are modified into small bladders, to trap small animals.

Question 13.
Define the term inflorescence. Explain the basis for the different types of inflorescence in flowering plants.
Answer:
The arrangement of flowers on the floral axis is termed as inflorescence. Depending on whether the apex gets converted into a flower or continues to grow, two major types of inflorescences are defined – racemose and cymose. In racemose type of inflorescence the main axis continues to grow, the flowers are borne laterally in an acropetal succession.

In cymose type of inflorescence the main axis terminates in a flower, hence is limited in growth. The flowers are borne in a basipetal order, as depicted in figure.

Question 14.
Write the floral formula of a actinomorphic, bisexual, hypogynous flower with five united sepals, five free petals, five f free stamens and two united carpels with superior ovary and axile placentation.
Answer:
Floral formula

Question 15.
Describe the arrangement of floral members in relation to their ‘ insertion on thalamus.
Answer:
A flower is a condensed specialised reproductive shoot found in angiosperms. The stalk of the flower is known as pedicel. The tip of the pedicel or the base of the flower has a broad highly condensed multinodal region called thalamus. The floral parts of a flower are present on the thalamus. Starting from below they are green sepals or calyx, coloured petals or corolla, stamens or androecium and carpels or gynoecium.