Class 10 - Biology – CH-6 - Life Processes PDF Download

 Page 1


Class 10 - Biology – CH-6 - Life Processes  
 
 
 
Q1. The kidneys in human beings are a part of the system for 
(a) nutrition. 
(b) respiration. 
(c) excretion. 
(d) transportation. 
 
Answer: (c) excretion. 
 
Q2. The xylem in plants are responsible for 
(a) transport of water. 
(b) transport of food. 
(c) transport of amino acids. 
(d) transport of oxygen. 
 
Answer: (a) transport of water. 
 
 
 
Q3. The autotrophic mode of nutrition requires 
(a) carbon dioxide and water. 
(b) chlorophyll. 
(c) sunlight. 
(d) all of the above. 
 
Answer: (d) All of the above 
 
Q4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in 
(a) cytoplasm. 
(b) mitochondria. 
(c) chloroplast. 
(d) nucleus. 
 
Answer: (b) mitochondria 
 
 
Q5. Movement of food through oesophagus is due to 
(a) Lubrication by saliva 
(b) Peristalsis 
(c) Gravitational Pull 
(d) All of the above 
 
Answer: (b) Peristalsis 
 
Q6. Where is bile produced? 
(a) Gall bladder 
(b) Blood 
(c) Liver 
(d) Spleen 
 
Answer: (c) Liver 
 
Q7: In normal expiration, the diaphragm is 
(a) Arched 
(b) Flattened 
(c) Perforated 
Page 2


Class 10 - Biology – CH-6 - Life Processes  
 
 
 
Q1. The kidneys in human beings are a part of the system for 
(a) nutrition. 
(b) respiration. 
(c) excretion. 
(d) transportation. 
 
Answer: (c) excretion. 
 
Q2. The xylem in plants are responsible for 
(a) transport of water. 
(b) transport of food. 
(c) transport of amino acids. 
(d) transport of oxygen. 
 
Answer: (a) transport of water. 
 
 
 
Q3. The autotrophic mode of nutrition requires 
(a) carbon dioxide and water. 
(b) chlorophyll. 
(c) sunlight. 
(d) all of the above. 
 
Answer: (d) All of the above 
 
Q4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in 
(a) cytoplasm. 
(b) mitochondria. 
(c) chloroplast. 
(d) nucleus. 
 
Answer: (b) mitochondria 
 
 
Q5. Movement of food through oesophagus is due to 
(a) Lubrication by saliva 
(b) Peristalsis 
(c) Gravitational Pull 
(d) All of the above 
 
Answer: (b) Peristalsis 
 
Q6. Where is bile produced? 
(a) Gall bladder 
(b) Blood 
(c) Liver 
(d) Spleen 
 
Answer: (c) Liver 
 
Q7: In normal expiration, the diaphragm is 
(a) Arched 
(b) Flattened 
(c) Perforated 
(d) None of these 
 
Answer: (a) Arched 
 
Q8: The correct pathway of blood in circulatory system is 
(a) atria ? ventricles ? arteries ? veins 
(b) ventricles ? atria ? veins ? arteries 
(c) ventricles ? veins ? arteries ? atria 
(d) veins ? ventricles ? atria ? arteries 
 
Answer: (a) 
 
Q9: Respiration is a process in which  
(a) Energy is stored in the form of ADP 
(b) Energy is released and stored in the form of ATP 
(c) Energy is used up 
(d) Energy is not released at all. 
 
Answer: (b) Energy is released and stored in the form of ATP 
 
Q10: Name an organ which is part of two body systems. 
 
Answer: Pancreas which if part of 
? Endocrine System  
? Digestive System  
Q11: Why do raw bread taste sweeter on mastication? 
 
Answer: It is because salivary glands secrete Salivary Amylase which converts starch into sugars. 
 
Q12: How are fats digested in our bodies? Where does this process take place?  
Answer: The small intestine is the site of the complete digestion of fats. Fats are present in the 
intestine in the form of large globules which makes it difficult for enzymes to act on them. Bile juice 
from the liver accomplishes this. Bile salts emulsify these large globules of fats and break them down 
into smaller globules increasing the efficiency of enzyme action. The pancreas secretes pancreatic 
juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down 
emulsified fats. The walls of the small intestine contain glands which secrete intestinal juice. The 
enzymes present in it finally convert the fats into fatty acids and glycerol. 
 
Q13: What is the role of saliva in the digestion of food?  
Answer: Saliva is a fluid which is secreted by the salivary glands. It helps in digestion of food by 
following ways: 
1. Saliva contains a digestive enzyme called salivary amylase, which breaks down starch into 
sugars (maltose).  
2. It cleans the mouth cavity and tends to destroy germs that cause teeth decay. It contains 
lysozymes which help in destroying the bacteria.  
3. It moistens and lubricates food which again helps in swallowing.  
4. It acts as solvent, dissolving some food particles to stimulate taste buds of the tongue.  
Q14: Why will simple diffusion not meet the requirement of human beings? 
Answer: All cells of body are not in direct contact with the environment. In humans the energy 
requirements are high. Waste produced is more due to active metabolism. Therefore simple diffusion 
does not meet the oxygen requirement of human beings. 
 
Q15: What criteria do we use to decide whether something is alive?  
Answer: Following criteria may be used to define whether something is alive: 
Page 3


Class 10 - Biology – CH-6 - Life Processes  
 
 
 
Q1. The kidneys in human beings are a part of the system for 
(a) nutrition. 
(b) respiration. 
(c) excretion. 
(d) transportation. 
 
Answer: (c) excretion. 
 
Q2. The xylem in plants are responsible for 
(a) transport of water. 
(b) transport of food. 
(c) transport of amino acids. 
(d) transport of oxygen. 
 
Answer: (a) transport of water. 
 
 
 
Q3. The autotrophic mode of nutrition requires 
(a) carbon dioxide and water. 
(b) chlorophyll. 
(c) sunlight. 
(d) all of the above. 
 
Answer: (d) All of the above 
 
Q4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in 
(a) cytoplasm. 
(b) mitochondria. 
(c) chloroplast. 
(d) nucleus. 
 
Answer: (b) mitochondria 
 
 
Q5. Movement of food through oesophagus is due to 
(a) Lubrication by saliva 
(b) Peristalsis 
(c) Gravitational Pull 
(d) All of the above 
 
Answer: (b) Peristalsis 
 
Q6. Where is bile produced? 
(a) Gall bladder 
(b) Blood 
(c) Liver 
(d) Spleen 
 
Answer: (c) Liver 
 
Q7: In normal expiration, the diaphragm is 
(a) Arched 
(b) Flattened 
(c) Perforated 
(d) None of these 
 
Answer: (a) Arched 
 
Q8: The correct pathway of blood in circulatory system is 
(a) atria ? ventricles ? arteries ? veins 
(b) ventricles ? atria ? veins ? arteries 
(c) ventricles ? veins ? arteries ? atria 
(d) veins ? ventricles ? atria ? arteries 
 
Answer: (a) 
 
Q9: Respiration is a process in which  
(a) Energy is stored in the form of ADP 
(b) Energy is released and stored in the form of ATP 
(c) Energy is used up 
(d) Energy is not released at all. 
 
Answer: (b) Energy is released and stored in the form of ATP 
 
Q10: Name an organ which is part of two body systems. 
 
Answer: Pancreas which if part of 
? Endocrine System  
? Digestive System  
Q11: Why do raw bread taste sweeter on mastication? 
 
Answer: It is because salivary glands secrete Salivary Amylase which converts starch into sugars. 
 
Q12: How are fats digested in our bodies? Where does this process take place?  
Answer: The small intestine is the site of the complete digestion of fats. Fats are present in the 
intestine in the form of large globules which makes it difficult for enzymes to act on them. Bile juice 
from the liver accomplishes this. Bile salts emulsify these large globules of fats and break them down 
into smaller globules increasing the efficiency of enzyme action. The pancreas secretes pancreatic 
juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down 
emulsified fats. The walls of the small intestine contain glands which secrete intestinal juice. The 
enzymes present in it finally convert the fats into fatty acids and glycerol. 
 
Q13: What is the role of saliva in the digestion of food?  
Answer: Saliva is a fluid which is secreted by the salivary glands. It helps in digestion of food by 
following ways: 
1. Saliva contains a digestive enzyme called salivary amylase, which breaks down starch into 
sugars (maltose).  
2. It cleans the mouth cavity and tends to destroy germs that cause teeth decay. It contains 
lysozymes which help in destroying the bacteria.  
3. It moistens and lubricates food which again helps in swallowing.  
4. It acts as solvent, dissolving some food particles to stimulate taste buds of the tongue.  
Q14: Why will simple diffusion not meet the requirement of human beings? 
Answer: All cells of body are not in direct contact with the environment. In humans the energy 
requirements are high. Waste produced is more due to active metabolism. Therefore simple diffusion 
does not meet the oxygen requirement of human beings. 
 
Q15: What criteria do we use to decide whether something is alive?  
Answer: Following criteria may be used to define whether something is alive: 
1. It is an organized system of molecules that captures energy and nutrients to grow by 
molecular movements,  
2. It has the ability to reproduce at some point in its life cycle, and  
3. It has the potential to evolve in response to changes in the environment.  
Q16: After long running, you may experience cramps in your leg muscles. Whats the reason 
behind this? 
Answer: It is due to sudden build up of lactic acid (because of lack of oxygen) in our muscles after 
long exercise. It causes muscular cramps in our leg muscles. 
 
Q17: What processes would you consider essential for maintaining life?  
Answer: Various life processes are essential for maintaining life. Some are: 
? Nutrition  
? Respiration  
? Excretion  
? Transportation  
Q18: How do villi enhance absorption of food in the intestine? 
Answer: 
? Increased surface area  
? Highly vascular  
Q19: Why bile juice is considered important even though it does not contain any digestive 
enzymes? 
Answer: Bile juice is important for the following reasons: 
1. It contains bile salts and bile pigments that emulsify fats.  
2. Contains NaHCO
3
 that neutralizes the acidic medium of the food in small intestine.  
 
Q20: Which organs secrete the following enzymes: 
(i) Trypsin 
(ii) Pepsin 
Answer: (i) Trypsin - Pancreas (ii) Pepsin - Gastric lining of Stomach 
 
 
Q21: Name the factors that affect photosynthesis. 
Answer: 
? Light Intensity, its quality and duration.  
? Temperature  
? Water Availability  
? CO
3
 availability  
? Other Factors like age and histology of leaf, amount of chlorophyll present  
Q22: Name the vestigeal part of human alimentary canal? 
Answer: vermiform appendix or caecal 
 
Q23: What is the name given to rhythmic wave like manner occurring in alimentary canal? 
Answer: Peristalsis or Peristaltic movements 
Q24: The bark of woody plants is dead but the inner layers inside the bark are living. How do 
they get oxygen and release carbon dioxide? 
Answer: Through lenticels  
 
Q25: What are lenticels?  
Page 4


Class 10 - Biology – CH-6 - Life Processes  
 
 
 
Q1. The kidneys in human beings are a part of the system for 
(a) nutrition. 
(b) respiration. 
(c) excretion. 
(d) transportation. 
 
Answer: (c) excretion. 
 
Q2. The xylem in plants are responsible for 
(a) transport of water. 
(b) transport of food. 
(c) transport of amino acids. 
(d) transport of oxygen. 
 
Answer: (a) transport of water. 
 
 
 
Q3. The autotrophic mode of nutrition requires 
(a) carbon dioxide and water. 
(b) chlorophyll. 
(c) sunlight. 
(d) all of the above. 
 
Answer: (d) All of the above 
 
Q4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in 
(a) cytoplasm. 
(b) mitochondria. 
(c) chloroplast. 
(d) nucleus. 
 
Answer: (b) mitochondria 
 
 
Q5. Movement of food through oesophagus is due to 
(a) Lubrication by saliva 
(b) Peristalsis 
(c) Gravitational Pull 
(d) All of the above 
 
Answer: (b) Peristalsis 
 
Q6. Where is bile produced? 
(a) Gall bladder 
(b) Blood 
(c) Liver 
(d) Spleen 
 
Answer: (c) Liver 
 
Q7: In normal expiration, the diaphragm is 
(a) Arched 
(b) Flattened 
(c) Perforated 
(d) None of these 
 
Answer: (a) Arched 
 
Q8: The correct pathway of blood in circulatory system is 
(a) atria ? ventricles ? arteries ? veins 
(b) ventricles ? atria ? veins ? arteries 
(c) ventricles ? veins ? arteries ? atria 
(d) veins ? ventricles ? atria ? arteries 
 
Answer: (a) 
 
Q9: Respiration is a process in which  
(a) Energy is stored in the form of ADP 
(b) Energy is released and stored in the form of ATP 
(c) Energy is used up 
(d) Energy is not released at all. 
 
Answer: (b) Energy is released and stored in the form of ATP 
 
Q10: Name an organ which is part of two body systems. 
 
Answer: Pancreas which if part of 
? Endocrine System  
? Digestive System  
Q11: Why do raw bread taste sweeter on mastication? 
 
Answer: It is because salivary glands secrete Salivary Amylase which converts starch into sugars. 
 
Q12: How are fats digested in our bodies? Where does this process take place?  
Answer: The small intestine is the site of the complete digestion of fats. Fats are present in the 
intestine in the form of large globules which makes it difficult for enzymes to act on them. Bile juice 
from the liver accomplishes this. Bile salts emulsify these large globules of fats and break them down 
into smaller globules increasing the efficiency of enzyme action. The pancreas secretes pancreatic 
juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down 
emulsified fats. The walls of the small intestine contain glands which secrete intestinal juice. The 
enzymes present in it finally convert the fats into fatty acids and glycerol. 
 
Q13: What is the role of saliva in the digestion of food?  
Answer: Saliva is a fluid which is secreted by the salivary glands. It helps in digestion of food by 
following ways: 
1. Saliva contains a digestive enzyme called salivary amylase, which breaks down starch into 
sugars (maltose).  
2. It cleans the mouth cavity and tends to destroy germs that cause teeth decay. It contains 
lysozymes which help in destroying the bacteria.  
3. It moistens and lubricates food which again helps in swallowing.  
4. It acts as solvent, dissolving some food particles to stimulate taste buds of the tongue.  
Q14: Why will simple diffusion not meet the requirement of human beings? 
Answer: All cells of body are not in direct contact with the environment. In humans the energy 
requirements are high. Waste produced is more due to active metabolism. Therefore simple diffusion 
does not meet the oxygen requirement of human beings. 
 
Q15: What criteria do we use to decide whether something is alive?  
Answer: Following criteria may be used to define whether something is alive: 
1. It is an organized system of molecules that captures energy and nutrients to grow by 
molecular movements,  
2. It has the ability to reproduce at some point in its life cycle, and  
3. It has the potential to evolve in response to changes in the environment.  
Q16: After long running, you may experience cramps in your leg muscles. Whats the reason 
behind this? 
Answer: It is due to sudden build up of lactic acid (because of lack of oxygen) in our muscles after 
long exercise. It causes muscular cramps in our leg muscles. 
 
Q17: What processes would you consider essential for maintaining life?  
Answer: Various life processes are essential for maintaining life. Some are: 
? Nutrition  
? Respiration  
? Excretion  
? Transportation  
Q18: How do villi enhance absorption of food in the intestine? 
Answer: 
? Increased surface area  
? Highly vascular  
Q19: Why bile juice is considered important even though it does not contain any digestive 
enzymes? 
Answer: Bile juice is important for the following reasons: 
1. It contains bile salts and bile pigments that emulsify fats.  
2. Contains NaHCO
3
 that neutralizes the acidic medium of the food in small intestine.  
 
Q20: Which organs secrete the following enzymes: 
(i) Trypsin 
(ii) Pepsin 
Answer: (i) Trypsin - Pancreas (ii) Pepsin - Gastric lining of Stomach 
 
 
Q21: Name the factors that affect photosynthesis. 
Answer: 
? Light Intensity, its quality and duration.  
? Temperature  
? Water Availability  
? CO
3
 availability  
? Other Factors like age and histology of leaf, amount of chlorophyll present  
Q22: Name the vestigeal part of human alimentary canal? 
Answer: vermiform appendix or caecal 
 
Q23: What is the name given to rhythmic wave like manner occurring in alimentary canal? 
Answer: Peristalsis or Peristaltic movements 
Q24: The bark of woody plants is dead but the inner layers inside the bark are living. How do 
they get oxygen and release carbon dioxide? 
Answer: Through lenticels  
 
Q25: What are lenticels?  
Answer: Lenticels are portions of the periderm (bark) with numerous intercellular spaces. Their 
purpose is to allow gas exchange through the compactly arranged cork cells of the bark, which 
otherwise presents an impermeable barrier to the passage of water and gases.  
 
 
Q26: How does photosynthesis occur? 
Answer: The process of photosynthesis is completed in two steps: 
1. light reaction  
2. dark reaction  
i) Light reaction: The first step of photosynthesis occurs in the presence of light. During this step, 
chlorophyll contained in the chloroplast of plant cells absorbs light energy. This energy is converted 
into another form, which can be supplied for the completion of the dark reaction. 
 
ii) Dark reaction: This second step of photosynthesis does not require light, and is called dark 
reaction. It can also carry on in the presence of light. During this step, energy generated during light 
reaction is used to combine carbon dioxide and water molecules to form energy rich compounds, 
such as glucose. Oxygen is also released in this process. 
 
The following equation summarizes the raw materials and products of photosynthetic process: 
 
RAW MATERIALS PRODUCTS 
sunlight 
6CO2 + 12H2O ----------------> C
6
H
12
O
6
 + 6H
2
O + 6O
2
 
carbon water chlorophyll glucose water oxygen 
dioxide 
 
Q27: Name the mode of nutrition in an organism that uses simple substances like CO2 and 
water to prepare food inside its body? 
Answer: Autotrophic mode of nutrition. 
 
Q28: What are the differences between autotrophic nutrition and heterotrophic nutrition?  
Answer: 
 
Autotrophic 
Nutrition 
Hetrotrophic 
Nutrition 
1 
Green plants are self-dependent, because they 
synthesize their own food materials by photosynthesis. 
Such mode of nutrition is 
described as autotrophic nutrition. 
Organisms which depend upon plants or other 
organisms for their nutrition.  
2 Green Plants (producers) are autotrophs. 
Non-Green Plants, Animals, Parasites are 
hetrotrophs (consumers). 
 
Q29: Read following statements from A to E and identify the relevant life process from the 
following word list. 
growth, transport, synthesis, regulation, nutrition 
 
A. A butterfly sucking the nectar from the flowers in a garden. 
B. A boy shouts with excitement when his school team wins the match on the last ball. 
C. After finishing lunch, Mohan's blood distributes the food molecules to different cells of his body. 
D. Green plants prepares starch (complex substance) from simpler chemicals. 
E. Radha finds her height has increased by 4 cm since her last birthday. 
 
Answer:  
A-nutrition 
B- regulation 
C- transport 
D- synthesis 
E- growth 
Page 5


Class 10 - Biology – CH-6 - Life Processes  
 
 
 
Q1. The kidneys in human beings are a part of the system for 
(a) nutrition. 
(b) respiration. 
(c) excretion. 
(d) transportation. 
 
Answer: (c) excretion. 
 
Q2. The xylem in plants are responsible for 
(a) transport of water. 
(b) transport of food. 
(c) transport of amino acids. 
(d) transport of oxygen. 
 
Answer: (a) transport of water. 
 
 
 
Q3. The autotrophic mode of nutrition requires 
(a) carbon dioxide and water. 
(b) chlorophyll. 
(c) sunlight. 
(d) all of the above. 
 
Answer: (d) All of the above 
 
Q4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in 
(a) cytoplasm. 
(b) mitochondria. 
(c) chloroplast. 
(d) nucleus. 
 
Answer: (b) mitochondria 
 
 
Q5. Movement of food through oesophagus is due to 
(a) Lubrication by saliva 
(b) Peristalsis 
(c) Gravitational Pull 
(d) All of the above 
 
Answer: (b) Peristalsis 
 
Q6. Where is bile produced? 
(a) Gall bladder 
(b) Blood 
(c) Liver 
(d) Spleen 
 
Answer: (c) Liver 
 
Q7: In normal expiration, the diaphragm is 
(a) Arched 
(b) Flattened 
(c) Perforated 
(d) None of these 
 
Answer: (a) Arched 
 
Q8: The correct pathway of blood in circulatory system is 
(a) atria ? ventricles ? arteries ? veins 
(b) ventricles ? atria ? veins ? arteries 
(c) ventricles ? veins ? arteries ? atria 
(d) veins ? ventricles ? atria ? arteries 
 
Answer: (a) 
 
Q9: Respiration is a process in which  
(a) Energy is stored in the form of ADP 
(b) Energy is released and stored in the form of ATP 
(c) Energy is used up 
(d) Energy is not released at all. 
 
Answer: (b) Energy is released and stored in the form of ATP 
 
Q10: Name an organ which is part of two body systems. 
 
Answer: Pancreas which if part of 
? Endocrine System  
? Digestive System  
Q11: Why do raw bread taste sweeter on mastication? 
 
Answer: It is because salivary glands secrete Salivary Amylase which converts starch into sugars. 
 
Q12: How are fats digested in our bodies? Where does this process take place?  
Answer: The small intestine is the site of the complete digestion of fats. Fats are present in the 
intestine in the form of large globules which makes it difficult for enzymes to act on them. Bile juice 
from the liver accomplishes this. Bile salts emulsify these large globules of fats and break them down 
into smaller globules increasing the efficiency of enzyme action. The pancreas secretes pancreatic 
juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down 
emulsified fats. The walls of the small intestine contain glands which secrete intestinal juice. The 
enzymes present in it finally convert the fats into fatty acids and glycerol. 
 
Q13: What is the role of saliva in the digestion of food?  
Answer: Saliva is a fluid which is secreted by the salivary glands. It helps in digestion of food by 
following ways: 
1. Saliva contains a digestive enzyme called salivary amylase, which breaks down starch into 
sugars (maltose).  
2. It cleans the mouth cavity and tends to destroy germs that cause teeth decay. It contains 
lysozymes which help in destroying the bacteria.  
3. It moistens and lubricates food which again helps in swallowing.  
4. It acts as solvent, dissolving some food particles to stimulate taste buds of the tongue.  
Q14: Why will simple diffusion not meet the requirement of human beings? 
Answer: All cells of body are not in direct contact with the environment. In humans the energy 
requirements are high. Waste produced is more due to active metabolism. Therefore simple diffusion 
does not meet the oxygen requirement of human beings. 
 
Q15: What criteria do we use to decide whether something is alive?  
Answer: Following criteria may be used to define whether something is alive: 
1. It is an organized system of molecules that captures energy and nutrients to grow by 
molecular movements,  
2. It has the ability to reproduce at some point in its life cycle, and  
3. It has the potential to evolve in response to changes in the environment.  
Q16: After long running, you may experience cramps in your leg muscles. Whats the reason 
behind this? 
Answer: It is due to sudden build up of lactic acid (because of lack of oxygen) in our muscles after 
long exercise. It causes muscular cramps in our leg muscles. 
 
Q17: What processes would you consider essential for maintaining life?  
Answer: Various life processes are essential for maintaining life. Some are: 
? Nutrition  
? Respiration  
? Excretion  
? Transportation  
Q18: How do villi enhance absorption of food in the intestine? 
Answer: 
? Increased surface area  
? Highly vascular  
Q19: Why bile juice is considered important even though it does not contain any digestive 
enzymes? 
Answer: Bile juice is important for the following reasons: 
1. It contains bile salts and bile pigments that emulsify fats.  
2. Contains NaHCO
3
 that neutralizes the acidic medium of the food in small intestine.  
 
Q20: Which organs secrete the following enzymes: 
(i) Trypsin 
(ii) Pepsin 
Answer: (i) Trypsin - Pancreas (ii) Pepsin - Gastric lining of Stomach 
 
 
Q21: Name the factors that affect photosynthesis. 
Answer: 
? Light Intensity, its quality and duration.  
? Temperature  
? Water Availability  
? CO
3
 availability  
? Other Factors like age and histology of leaf, amount of chlorophyll present  
Q22: Name the vestigeal part of human alimentary canal? 
Answer: vermiform appendix or caecal 
 
Q23: What is the name given to rhythmic wave like manner occurring in alimentary canal? 
Answer: Peristalsis or Peristaltic movements 
Q24: The bark of woody plants is dead but the inner layers inside the bark are living. How do 
they get oxygen and release carbon dioxide? 
Answer: Through lenticels  
 
Q25: What are lenticels?  
Answer: Lenticels are portions of the periderm (bark) with numerous intercellular spaces. Their 
purpose is to allow gas exchange through the compactly arranged cork cells of the bark, which 
otherwise presents an impermeable barrier to the passage of water and gases.  
 
 
Q26: How does photosynthesis occur? 
Answer: The process of photosynthesis is completed in two steps: 
1. light reaction  
2. dark reaction  
i) Light reaction: The first step of photosynthesis occurs in the presence of light. During this step, 
chlorophyll contained in the chloroplast of plant cells absorbs light energy. This energy is converted 
into another form, which can be supplied for the completion of the dark reaction. 
 
ii) Dark reaction: This second step of photosynthesis does not require light, and is called dark 
reaction. It can also carry on in the presence of light. During this step, energy generated during light 
reaction is used to combine carbon dioxide and water molecules to form energy rich compounds, 
such as glucose. Oxygen is also released in this process. 
 
The following equation summarizes the raw materials and products of photosynthetic process: 
 
RAW MATERIALS PRODUCTS 
sunlight 
6CO2 + 12H2O ----------------> C
6
H
12
O
6
 + 6H
2
O + 6O
2
 
carbon water chlorophyll glucose water oxygen 
dioxide 
 
Q27: Name the mode of nutrition in an organism that uses simple substances like CO2 and 
water to prepare food inside its body? 
Answer: Autotrophic mode of nutrition. 
 
Q28: What are the differences between autotrophic nutrition and heterotrophic nutrition?  
Answer: 
 
Autotrophic 
Nutrition 
Hetrotrophic 
Nutrition 
1 
Green plants are self-dependent, because they 
synthesize their own food materials by photosynthesis. 
Such mode of nutrition is 
described as autotrophic nutrition. 
Organisms which depend upon plants or other 
organisms for their nutrition.  
2 Green Plants (producers) are autotrophs. 
Non-Green Plants, Animals, Parasites are 
hetrotrophs (consumers). 
 
Q29: Read following statements from A to E and identify the relevant life process from the 
following word list. 
growth, transport, synthesis, regulation, nutrition 
 
A. A butterfly sucking the nectar from the flowers in a garden. 
B. A boy shouts with excitement when his school team wins the match on the last ball. 
C. After finishing lunch, Mohan's blood distributes the food molecules to different cells of his body. 
D. Green plants prepares starch (complex substance) from simpler chemicals. 
E. Radha finds her height has increased by 4 cm since her last birthday. 
 
Answer:  
A-nutrition 
B- regulation 
C- transport 
D- synthesis 
E- growth 
 
 
Q30: What is osmoregulation?  
 
Answer: The regulation of the water content of the cell is called osmoregulation. 
 
Q31: What are the different ways in which glucose is oxidized to provide energy in various 
organisms? 
 
Answer: Breaking down of glucouse involves two step process. In the first step, it is broken into three 
carbon molecule called pyruvate. The pyruvate is further broken down into energy in following 
different ways in various organisms: 
1. Aerobic Respiration: In this case, pyruvate is broken down into water and carbon dioxide 
along with release of energy. It commonly occurs in mitochondria of cells.  
2. Anaerobic Respiration in Yeast: In yeast cells during fermentation pyruvate is converted into 
ethanol and carbon dioxide in the absence of oxygen.  
3. Anaerobic Respiration in Muscles: Due to lack of oxygen, e.g. during vigorous running or 
exercise, in human muscles, pyruvate is converted into lactic acid.  
 
Q31: Which organ of the plant body helps in osmo-regulation? 
 
Answer: Leaves 
 
Q32: Which organelle of the cell in animals helps in osmo-regulation?  
 
Answer: Contractile Vacuole. 
 
Q33: If kidney fails to reabsorb water, the tissues would 
(a) remain unaffected 
(b) shrink to shrivel 
(c) absorb water from blood 
(d) take more oxygen from blood 
 
Answer: (c) absorb water from blood. This condition is called Oedma or Dropsy 
 
Q34: How does transpiration pull help in ascent of sap? 
 
Answer: Water column builds up as a result of cohesion and adhesion forces. The negative pressure 
in the upper tissues results in upward pull of water. 
 
Q35: In what form excretion takes place in plants? 
 
Answer: Plants produce secondary metabolites like organic acids, tannin, resins, latex, gums etc. 
 
Q36: What are the components of the transport system in highly organised plants? 
 
Answer: The transport system of organised plants consist of xylem and phloem. Xylem which have 
vessels and tracheids which transport water and minerals from root to other parts of the plant. Phloem 
which consists of sieve tubes, sieve cells and companion cells transport food from leaves to storage 
organs and other parts of the plant. In xylem, the transport is unidirectional i.e. from root upward while 
in phloem, it is bidirectional.