Class 11 Biology Sample Solution- 7 | Biology for Grade 11 PDF Download

 Page 1


  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
CBSE 
Class XI Biology 
Sample Paper – 7 Solution 
 
SECTION A 
 
1. They are called roundworms because their body is circular in cross-section. 
 
2. When the vascular bundle lacks cambium, it is referred to as closed. 
 
3. A metacentric chromosome has the centromere at the centre and the two arms are 
equal in length. 
OR 
The smooth endoplasmic reticulum is the major site for the synthesis of lipids. 
 
4. Ubiquinol 
 
5. Bone marrow 
OR 
SAN can generate 70 –75 action potentials per minute. 
 
SECTION B 
 
6. The mutually beneficial or symbiotic association of a fungus with the root of a higher 
plant is known as mycorrhiza. 
The plant is immensely benefited from the association with the fungus. Fungal 
hyphae take part in the absorption of water, dissolving essential minerals present in the 
organic debris and handing over the same to the plant, absorbing inorganic salts 
present in the soil and producing various growth-promoting substances. The fungus in 
return is dependent on the higher plant for shelter and food. 
 
7. Oxygen in the blood is transported in the following two ways: 
i. As dissolved gas: About 1 –3% of oxygen is transported by blood in the dissolved 
form in the plasma of blood. 
ii. As oxyhaemoglobin: About 97 –99% of oxygen is transported in chemical 
combination with haemoglobin in red blood cells. 
 
8. Amylase is secreted by salivary glands and pancreas.  
Salivary glands secrete saliva which contains salivary amylase into the buccal cavity 
and converts starch to maltose.  
The pancreas secretes pancreatic juice containing pancreatic amylase into the 
duodenum. It acts on starch and breaks it into maltose. 
Page 2


  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
CBSE 
Class XI Biology 
Sample Paper – 7 Solution 
 
SECTION A 
 
1. They are called roundworms because their body is circular in cross-section. 
 
2. When the vascular bundle lacks cambium, it is referred to as closed. 
 
3. A metacentric chromosome has the centromere at the centre and the two arms are 
equal in length. 
OR 
The smooth endoplasmic reticulum is the major site for the synthesis of lipids. 
 
4. Ubiquinol 
 
5. Bone marrow 
OR 
SAN can generate 70 –75 action potentials per minute. 
 
SECTION B 
 
6. The mutually beneficial or symbiotic association of a fungus with the root of a higher 
plant is known as mycorrhiza. 
The plant is immensely benefited from the association with the fungus. Fungal 
hyphae take part in the absorption of water, dissolving essential minerals present in the 
organic debris and handing over the same to the plant, absorbing inorganic salts 
present in the soil and producing various growth-promoting substances. The fungus in 
return is dependent on the higher plant for shelter and food. 
 
7. Oxygen in the blood is transported in the following two ways: 
i. As dissolved gas: About 1 –3% of oxygen is transported by blood in the dissolved 
form in the plasma of blood. 
ii. As oxyhaemoglobin: About 97 –99% of oxygen is transported in chemical 
combination with haemoglobin in red blood cells. 
 
8. Amylase is secreted by salivary glands and pancreas.  
Salivary glands secrete saliva which contains salivary amylase into the buccal cavity 
and converts starch to maltose.  
The pancreas secretes pancreatic juice containing pancreatic amylase into the 
duodenum. It acts on starch and breaks it into maltose. 
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
9. In addition to the genomic DNA, many bacteria have small circular DNA outside the 
genomic DNA. These are called plasmids. 
Plasmid DNA confers certain unique characters such as resistance to antibiotics, fertility 
factor etc. 
OR 
Prosthetic Group Coenzyme 
(i) It is a non-protein group 
attached firmly to an apoenzyme. 
(ii) It requires a single apoenzyme 
for picking up and transferring a 
group. Example: Haem 
(i) It is a non-protein group 
attached loosely to complex 
macromolecules with three-
dimensional structures. 
(ii) It requires different apoenzymes 
for picking up and transferring a 
group. 
Examples: NAD
+
, NADP
+
 
 
 
10. Diatomaceous earth refers to the deposits of the nearly indestructible siliceous cell wall 
of diatoms in the ocean floor. 
Economic uses of diatomaceous earth: 
? It is used in filtration of oils and syrups. 
? It is used in polishing of metals. 
OR 
Chemosynthetic bacteria play an important role in the recycling of nutrients like 
nitrogen, iron, sulphur and phosphorus.  
 
11. Guard cells are specialised epidermal cells which surround the stoma. They possess 
chloroplasts and carry out photosynthesis. 
Functions of guard cells: 
? They regulate the opening and closing of stomata for the exchange of gases and 
transpiration.  
 
12. Structural formula 
                 
 
                                                     Uracil                                        Uridine 
Page 3


  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
CBSE 
Class XI Biology 
Sample Paper – 7 Solution 
 
SECTION A 
 
1. They are called roundworms because their body is circular in cross-section. 
 
2. When the vascular bundle lacks cambium, it is referred to as closed. 
 
3. A metacentric chromosome has the centromere at the centre and the two arms are 
equal in length. 
OR 
The smooth endoplasmic reticulum is the major site for the synthesis of lipids. 
 
4. Ubiquinol 
 
5. Bone marrow 
OR 
SAN can generate 70 –75 action potentials per minute. 
 
SECTION B 
 
6. The mutually beneficial or symbiotic association of a fungus with the root of a higher 
plant is known as mycorrhiza. 
The plant is immensely benefited from the association with the fungus. Fungal 
hyphae take part in the absorption of water, dissolving essential minerals present in the 
organic debris and handing over the same to the plant, absorbing inorganic salts 
present in the soil and producing various growth-promoting substances. The fungus in 
return is dependent on the higher plant for shelter and food. 
 
7. Oxygen in the blood is transported in the following two ways: 
i. As dissolved gas: About 1 –3% of oxygen is transported by blood in the dissolved 
form in the plasma of blood. 
ii. As oxyhaemoglobin: About 97 –99% of oxygen is transported in chemical 
combination with haemoglobin in red blood cells. 
 
8. Amylase is secreted by salivary glands and pancreas.  
Salivary glands secrete saliva which contains salivary amylase into the buccal cavity 
and converts starch to maltose.  
The pancreas secretes pancreatic juice containing pancreatic amylase into the 
duodenum. It acts on starch and breaks it into maltose. 
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
9. In addition to the genomic DNA, many bacteria have small circular DNA outside the 
genomic DNA. These are called plasmids. 
Plasmid DNA confers certain unique characters such as resistance to antibiotics, fertility 
factor etc. 
OR 
Prosthetic Group Coenzyme 
(i) It is a non-protein group 
attached firmly to an apoenzyme. 
(ii) It requires a single apoenzyme 
for picking up and transferring a 
group. Example: Haem 
(i) It is a non-protein group 
attached loosely to complex 
macromolecules with three-
dimensional structures. 
(ii) It requires different apoenzymes 
for picking up and transferring a 
group. 
Examples: NAD
+
, NADP
+
 
 
 
10. Diatomaceous earth refers to the deposits of the nearly indestructible siliceous cell wall 
of diatoms in the ocean floor. 
Economic uses of diatomaceous earth: 
? It is used in filtration of oils and syrups. 
? It is used in polishing of metals. 
OR 
Chemosynthetic bacteria play an important role in the recycling of nutrients like 
nitrogen, iron, sulphur and phosphorus.  
 
11. Guard cells are specialised epidermal cells which surround the stoma. They possess 
chloroplasts and carry out photosynthesis. 
Functions of guard cells: 
? They regulate the opening and closing of stomata for the exchange of gases and 
transpiration.  
 
12. Structural formula 
                 
 
                                                     Uracil                                        Uridine 
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
SECTION C 
 
13. Gymnosperms and angiosperms are classified separately because of the following 
reasons: 
i. The ovules are naked in gymnosperms but are enclosed inside the ovary in 
angiosperms. 
ii. In gymnosperms, the wood is non-porous, i.e. the vessels are absent. In 
angiosperms, the wood is porous, i.e. the vessels are present. 
iii. In gymnosperms, the endosperm is haploid and is formed before fertilisation and 
double fertilisation is absent, whereas in angiosperms, the endosperm is triploid 
and formed after double fertilisation. 
 
14.  Differences between adipose tissue and blood tissue: 
Adipose Tissue Blood Tissue 
(i) It is a loose connective tissue. 
(ii) The matrix has fibres. 
(iii) It is involved in the storage and 
metabolism of fats. 
(i) It is a fluid connective tissue. 
(ii) The matrix does not have any 
fibre. 
(iii) It is meant for circulation of 
various substances and 
respiratory gases. 
 
OR 
(a) Chondrocytes: 
? They are cartilage cells. 
? They are present at the tip of the nose, pinna of the ear and joints between 
adjacent vertebrae in the vertebral column.  
(b) Axon: 
? It is the longest process of a neuron which conducts impulses away from the cell 
body.  
? It is present in all nerve fibres.  
(c) Ciliated epithelium: 
? Cuboidal or columnar epithelial cells bearing cilia constitute ciliated epithelium. 
? It is found in bronchioles and fallopian tube.  
 
15.    
i. The pericycle is positioned just inner to the endodermis. 
ii. The protoxylem elements are towards the external surface, while the metaxylem 
elements are found towards the core. 
iii. Such arrangement of the xylem is called exarch. 
 
 
  
Page 4


  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
CBSE 
Class XI Biology 
Sample Paper – 7 Solution 
 
SECTION A 
 
1. They are called roundworms because their body is circular in cross-section. 
 
2. When the vascular bundle lacks cambium, it is referred to as closed. 
 
3. A metacentric chromosome has the centromere at the centre and the two arms are 
equal in length. 
OR 
The smooth endoplasmic reticulum is the major site for the synthesis of lipids. 
 
4. Ubiquinol 
 
5. Bone marrow 
OR 
SAN can generate 70 –75 action potentials per minute. 
 
SECTION B 
 
6. The mutually beneficial or symbiotic association of a fungus with the root of a higher 
plant is known as mycorrhiza. 
The plant is immensely benefited from the association with the fungus. Fungal 
hyphae take part in the absorption of water, dissolving essential minerals present in the 
organic debris and handing over the same to the plant, absorbing inorganic salts 
present in the soil and producing various growth-promoting substances. The fungus in 
return is dependent on the higher plant for shelter and food. 
 
7. Oxygen in the blood is transported in the following two ways: 
i. As dissolved gas: About 1 –3% of oxygen is transported by blood in the dissolved 
form in the plasma of blood. 
ii. As oxyhaemoglobin: About 97 –99% of oxygen is transported in chemical 
combination with haemoglobin in red blood cells. 
 
8. Amylase is secreted by salivary glands and pancreas.  
Salivary glands secrete saliva which contains salivary amylase into the buccal cavity 
and converts starch to maltose.  
The pancreas secretes pancreatic juice containing pancreatic amylase into the 
duodenum. It acts on starch and breaks it into maltose. 
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
9. In addition to the genomic DNA, many bacteria have small circular DNA outside the 
genomic DNA. These are called plasmids. 
Plasmid DNA confers certain unique characters such as resistance to antibiotics, fertility 
factor etc. 
OR 
Prosthetic Group Coenzyme 
(i) It is a non-protein group 
attached firmly to an apoenzyme. 
(ii) It requires a single apoenzyme 
for picking up and transferring a 
group. Example: Haem 
(i) It is a non-protein group 
attached loosely to complex 
macromolecules with three-
dimensional structures. 
(ii) It requires different apoenzymes 
for picking up and transferring a 
group. 
Examples: NAD
+
, NADP
+
 
 
 
10. Diatomaceous earth refers to the deposits of the nearly indestructible siliceous cell wall 
of diatoms in the ocean floor. 
Economic uses of diatomaceous earth: 
? It is used in filtration of oils and syrups. 
? It is used in polishing of metals. 
OR 
Chemosynthetic bacteria play an important role in the recycling of nutrients like 
nitrogen, iron, sulphur and phosphorus.  
 
11. Guard cells are specialised epidermal cells which surround the stoma. They possess 
chloroplasts and carry out photosynthesis. 
Functions of guard cells: 
? They regulate the opening and closing of stomata for the exchange of gases and 
transpiration.  
 
12. Structural formula 
                 
 
                                                     Uracil                                        Uridine 
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
SECTION C 
 
13. Gymnosperms and angiosperms are classified separately because of the following 
reasons: 
i. The ovules are naked in gymnosperms but are enclosed inside the ovary in 
angiosperms. 
ii. In gymnosperms, the wood is non-porous, i.e. the vessels are absent. In 
angiosperms, the wood is porous, i.e. the vessels are present. 
iii. In gymnosperms, the endosperm is haploid and is formed before fertilisation and 
double fertilisation is absent, whereas in angiosperms, the endosperm is triploid 
and formed after double fertilisation. 
 
14.  Differences between adipose tissue and blood tissue: 
Adipose Tissue Blood Tissue 
(i) It is a loose connective tissue. 
(ii) The matrix has fibres. 
(iii) It is involved in the storage and 
metabolism of fats. 
(i) It is a fluid connective tissue. 
(ii) The matrix does not have any 
fibre. 
(iii) It is meant for circulation of 
various substances and 
respiratory gases. 
 
OR 
(a) Chondrocytes: 
? They are cartilage cells. 
? They are present at the tip of the nose, pinna of the ear and joints between 
adjacent vertebrae in the vertebral column.  
(b) Axon: 
? It is the longest process of a neuron which conducts impulses away from the cell 
body.  
? It is present in all nerve fibres.  
(c) Ciliated epithelium: 
? Cuboidal or columnar epithelial cells bearing cilia constitute ciliated epithelium. 
? It is found in bronchioles and fallopian tube.  
 
15.    
i. The pericycle is positioned just inner to the endodermis. 
ii. The protoxylem elements are towards the external surface, while the metaxylem 
elements are found towards the core. 
iii. Such arrangement of the xylem is called exarch. 
 
 
  
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
16.  
i. Chondrocytes are cells of cartilage. These are large, rounded, mature cells occurring 
in groups in the matrix of the cartilage. The cartilage is found in the pinna, tip of the 
nose, outer ear joints, between adjacent bones of the vertebral column, limbs and 
hands in adults.  
ii. Axon is the tail-like structure of a neuron. Each axon is a long, cylindrical process of 
the nerve cell. It arises from the cyton and conducts nerve impulses away from the 
cell body. It ends in a group of branches called terminal arborisations. These are 
present in the entire body. 
iii. Ciliated epithelium consists of cells which bear fine, vibratile cytoplasmic processes 
called cilia on its free surface. Cilia help to trap and clear dust and foreign particles. 
It is found in the inner lining of bronchioles, urinary tubules of the kidneys, nasal 
passage, oviducts, ventricles of the brain etc. 
 
17.  Significance of meiosis: 
i. Formation of gametes: Meiosis produces gametes for sexual reproduction. 
ii. Crossing over: It introduces new combination of traits or variations. 
iii. Maintenance of chromosome number: Meiosis reduces the number of chromosomes 
to half in the gametes so that fertilisation may restore the original diploid number in 
the zygote. 
OR 
Events in the prophase of animal cells: 
? Prophase is marked by the initiation of condensation of chromatin material. 
? Nuclear membrane and nucleolus start disappearing. 
? In animal cells, the centrioles that have been formed by duplication, start moving 
towards opposite poles of the cell. 
? Cells at the end of the prophase do not have nucleolus, nuclear membrane, 
endoplasmic reticulum and Golgi bodies.  
 
 
 
 
  
Page 5


  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
CBSE 
Class XI Biology 
Sample Paper – 7 Solution 
 
SECTION A 
 
1. They are called roundworms because their body is circular in cross-section. 
 
2. When the vascular bundle lacks cambium, it is referred to as closed. 
 
3. A metacentric chromosome has the centromere at the centre and the two arms are 
equal in length. 
OR 
The smooth endoplasmic reticulum is the major site for the synthesis of lipids. 
 
4. Ubiquinol 
 
5. Bone marrow 
OR 
SAN can generate 70 –75 action potentials per minute. 
 
SECTION B 
 
6. The mutually beneficial or symbiotic association of a fungus with the root of a higher 
plant is known as mycorrhiza. 
The plant is immensely benefited from the association with the fungus. Fungal 
hyphae take part in the absorption of water, dissolving essential minerals present in the 
organic debris and handing over the same to the plant, absorbing inorganic salts 
present in the soil and producing various growth-promoting substances. The fungus in 
return is dependent on the higher plant for shelter and food. 
 
7. Oxygen in the blood is transported in the following two ways: 
i. As dissolved gas: About 1 –3% of oxygen is transported by blood in the dissolved 
form in the plasma of blood. 
ii. As oxyhaemoglobin: About 97 –99% of oxygen is transported in chemical 
combination with haemoglobin in red blood cells. 
 
8. Amylase is secreted by salivary glands and pancreas.  
Salivary glands secrete saliva which contains salivary amylase into the buccal cavity 
and converts starch to maltose.  
The pancreas secretes pancreatic juice containing pancreatic amylase into the 
duodenum. It acts on starch and breaks it into maltose. 
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
9. In addition to the genomic DNA, many bacteria have small circular DNA outside the 
genomic DNA. These are called plasmids. 
Plasmid DNA confers certain unique characters such as resistance to antibiotics, fertility 
factor etc. 
OR 
Prosthetic Group Coenzyme 
(i) It is a non-protein group 
attached firmly to an apoenzyme. 
(ii) It requires a single apoenzyme 
for picking up and transferring a 
group. Example: Haem 
(i) It is a non-protein group 
attached loosely to complex 
macromolecules with three-
dimensional structures. 
(ii) It requires different apoenzymes 
for picking up and transferring a 
group. 
Examples: NAD
+
, NADP
+
 
 
 
10. Diatomaceous earth refers to the deposits of the nearly indestructible siliceous cell wall 
of diatoms in the ocean floor. 
Economic uses of diatomaceous earth: 
? It is used in filtration of oils and syrups. 
? It is used in polishing of metals. 
OR 
Chemosynthetic bacteria play an important role in the recycling of nutrients like 
nitrogen, iron, sulphur and phosphorus.  
 
11. Guard cells are specialised epidermal cells which surround the stoma. They possess 
chloroplasts and carry out photosynthesis. 
Functions of guard cells: 
? They regulate the opening and closing of stomata for the exchange of gases and 
transpiration.  
 
12. Structural formula 
                 
 
                                                     Uracil                                        Uridine 
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
SECTION C 
 
13. Gymnosperms and angiosperms are classified separately because of the following 
reasons: 
i. The ovules are naked in gymnosperms but are enclosed inside the ovary in 
angiosperms. 
ii. In gymnosperms, the wood is non-porous, i.e. the vessels are absent. In 
angiosperms, the wood is porous, i.e. the vessels are present. 
iii. In gymnosperms, the endosperm is haploid and is formed before fertilisation and 
double fertilisation is absent, whereas in angiosperms, the endosperm is triploid 
and formed after double fertilisation. 
 
14.  Differences between adipose tissue and blood tissue: 
Adipose Tissue Blood Tissue 
(i) It is a loose connective tissue. 
(ii) The matrix has fibres. 
(iii) It is involved in the storage and 
metabolism of fats. 
(i) It is a fluid connective tissue. 
(ii) The matrix does not have any 
fibre. 
(iii) It is meant for circulation of 
various substances and 
respiratory gases. 
 
OR 
(a) Chondrocytes: 
? They are cartilage cells. 
? They are present at the tip of the nose, pinna of the ear and joints between 
adjacent vertebrae in the vertebral column.  
(b) Axon: 
? It is the longest process of a neuron which conducts impulses away from the cell 
body.  
? It is present in all nerve fibres.  
(c) Ciliated epithelium: 
? Cuboidal or columnar epithelial cells bearing cilia constitute ciliated epithelium. 
? It is found in bronchioles and fallopian tube.  
 
15.    
i. The pericycle is positioned just inner to the endodermis. 
ii. The protoxylem elements are towards the external surface, while the metaxylem 
elements are found towards the core. 
iii. Such arrangement of the xylem is called exarch. 
 
 
  
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
16.  
i. Chondrocytes are cells of cartilage. These are large, rounded, mature cells occurring 
in groups in the matrix of the cartilage. The cartilage is found in the pinna, tip of the 
nose, outer ear joints, between adjacent bones of the vertebral column, limbs and 
hands in adults.  
ii. Axon is the tail-like structure of a neuron. Each axon is a long, cylindrical process of 
the nerve cell. It arises from the cyton and conducts nerve impulses away from the 
cell body. It ends in a group of branches called terminal arborisations. These are 
present in the entire body. 
iii. Ciliated epithelium consists of cells which bear fine, vibratile cytoplasmic processes 
called cilia on its free surface. Cilia help to trap and clear dust and foreign particles. 
It is found in the inner lining of bronchioles, urinary tubules of the kidneys, nasal 
passage, oviducts, ventricles of the brain etc. 
 
17.  Significance of meiosis: 
i. Formation of gametes: Meiosis produces gametes for sexual reproduction. 
ii. Crossing over: It introduces new combination of traits or variations. 
iii. Maintenance of chromosome number: Meiosis reduces the number of chromosomes 
to half in the gametes so that fertilisation may restore the original diploid number in 
the zygote. 
OR 
Events in the prophase of animal cells: 
? Prophase is marked by the initiation of condensation of chromatin material. 
? Nuclear membrane and nucleolus start disappearing. 
? In animal cells, the centrioles that have been formed by duplication, start moving 
towards opposite poles of the cell. 
? Cells at the end of the prophase do not have nucleolus, nuclear membrane, 
endoplasmic reticulum and Golgi bodies.  
 
 
 
 
  
  
 
CBSE XI  |  BIOLOGY 
Sample Paper – 7 Solution 
 
     
 
18. Leucoplasts are the colourless plastids of varied shapes and sizes with stored nutrients. 
There are three types of special leucoplasts: 
i. Amyloplasts: These are starch-containing leucoplasts.  
ii. Elaioplasts: These are colourless plastids which store fat. 
iii. Aleuroplasts: These plastids contain protein. 
 
19.  A mesosome is a membrane complex formed by infolding of the plasma membrane in 
prokaryotic cells. If a mesosome is attached to the nucleoid, it is called septal 
mesosome. A mesosome free from the nucleoid is called lateral mesosome. The lateral 
mesosome is rich in respiratory enzymes and thus takes part in respiration. The septal 
mesosome takes part in separation of daughter nucleoids, formation of the plasma 
membrane for rapid elongation and formation of the septum.  
 
20.   
Glycolysis Fermentation 
(i) It is the first step of respiration 
which occurs without requirement 
of oxygen and is common to both 
aerobic and anaerobic modes of 
respiration. 
(ii) Glycolysis produces pyruvic acid. 
(iii) It produces two molecules of NADH 
per glucose molecule. 
(i) It is anaerobic respiration or 
respiration which does not require 
oxygen. 
(ii) Fermentation produces different 
products. The common ones are 
ethanol (and CO
2
) and lactic acid. 
(iii) It generally utilises NADH produced 
during glycolysis. 
  
 
21.  Bulliform cells are modified, large, empty and colourless adaxial epidermal cells along 
the veins found in the leaves of grasses. They are also called motor cells. 
Functions: When the bulliform cells have absorbed water and are turgid, the leaf 
surface is exposed. When they are flaccid due to water stress, they make the leaves curl 
inwards to minimise water loss. 
OR 
(a) Special features of C4 plants: 
i. They have a special type of leaf anatomy (Kranz anatomy).  
ii. They tolerate higher temperatures. 
iii. They show a response to high light intensities. 
iv. They lack a process called photorespiration and thus have greater productivity 
of biomass. 
(b) Mass flow is the movement of substances in bulk from one point to another as a 
result of pressure differences between the two points.