Class 10 Science: Life Processes important questions
Life Processes is a chapter of Class 10 Science for the CBSE. These 24 questions are marked Very Important, Important or Practice, and each answer has been checked by our team. Use them to revise, not as a prediction of what will come in the exam.
Practice · 1 marks
1. Assertion: Height in pea plants is controlled by efficiency of enzymes and is thus genetically controlled. Reason: Cellular DNA is the information source for making proteins in the cell.
(a) Both A and R are true and R is the correct explanation of A
Practice · 1 marks
2. Assertion: Amphibians can tolerate mixing of oxygenated and deoxygenated blood. Reason: Amphibians are animals with two chambered heart
(c) A is true but R is false
Important · 2 marks
3. Patients whose gallbladder are removed are recommended to eat less oily food. Why?
Gallbladder stores bile which helps in emulsification of lipids. In the absence of stored bile, emulsification of fats will be negligible/ affected/ less and thus fat digestion will be slow. Hence there are such diet restrictions.
Important · 2 marks
4. Name the substances other than water, that are reabsorbed during urine formation. What are the two parameters that decide the amount of water that is reabsorbed in the kidney?
Glucose, amino acids, salts and a major amount of water are selectively re-absorbed as the urine flows along the tube. The amount of water reabsorbed depends on how much excess water there is in the body, and on how much of dissolved waste there is to be excreted
Important · 3 marks
5. The leaves of a plant were covered with aluminium foil, how would it affect the physiology of the plant? OR How is lymph an important fluid involved in transportation? If lymphatic vessels get blocked, how would it affect the human body? Elaborate.
No photosynthesis will occur so no glucose will be made. Also no respiration will take place as no Oxygen will be taken in. No transpiration will occur so there would be no upward movement of water or minerals from the soil as there will be no transpirational pull. Temperature regulation of leaf surface will be affected. OR Lymph carries digested and absorbed fat from the intestine (1) and drains excess fluid from extracellular space back into the blood (1). Blockage of lymphatic system will lead to water retention and poor fat absorption in the body (1- any one)
Practice · 1 marks
6. Generally food is broken and absorbed within the body of organisms. In which of the following organisms is it done outside the body? a) Amoeba b) Mushroom c) Paramoecium d) Lice
b) Mushroom
Practice · 1 marks
7. A sportsman, after a long break of his routine exercise, suffered muscular cramps during a heavy exercise session. This happened due to: a) lack of carbon dioxide and formation of pyruvate. b) presence of oxygen and formation of ethanol. c) lack of oxygen and formation of lactic acid. d) lack of oxygen and formation of carbon dioxide.
c) lack of oxygen and formation of lactic acid.
Important · 2 marks
8. What is the purpose of making urine in the human body? Name the organs that stores and releases the urine. OR Why do arteries have thick and elastic walls whereas veins have valves?
To filter out nitrogenous waste products like urea and uric acid from the blood in humans. Organ for storage: Urinary Bladder Organ for release: Urethra OR The blood emerges from the heart under high pressure and flows through arteries. Hence, to bear this pressure the arteries have thick and elastic walls. -Veins have valves to ensure that the blood flows in one direction only.
Practice · 1 marks
9. During cellular oxidation of Glucose, ATP is produced along with formation of other products in this reaction. Which of the following events is associated with production of maximum ATP molecules per molecule of Glucose during this process? Synthesis of A. ethanol in yeast B. lactic acid in muscle cells C. carbon dioxide in yeast cells D. carbon dioxide in human cells
D. carbon dioxide in human cells
Practice · 1 marks
10. During which of the following stages of the circulation of blood in a normal human being, the oxygenated blood is pumped to all parts of the body? A. contraction of the left atrium B. contraction of left ventricle C. relaxation of the right atrium D. relaxation of the right ventricle
B. contraction of left ventricle.
Practice · 1 marks
11. Which of the following adaptations in herbivores helps in digestions of cellulose? A. Longer large intestine B. Smaller large intestine C. Smaller small intestine D. Longer small intestine
D. Longer small intestine.
Important · 2 marks
12. Differentiate between alveoli and nephron on the basis of the following points: S. No. Feature Alveoli Nephron 1 Structure and location 2 Function
S. No. Feature Alveoli Nephron 1 Structure Balloon like structures Tubular structure and present at the terminal present in location ends of bronchioles in kidneys lungs 2 Function Exchange of gases Filtration of blood to form urine
Important · 2 marks
13. A. List the steps for the synthesis of glucose by the plants. What special feature is found in desert plants related to this process? OR B. Explain the role of the following enzymes in the process of digestion of food in humans: (i) Salivary amylase (ii) Pepsin (iii) Trypsin (iv) Lipase
A. Steps of synthesis of glucose in plants: - Absorption of light energy by chlorophyll - Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen - Reduction of carbon dioxide into carbohydrates. - Desert plants take up carbon dioxide at night and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day. OR B. - Salivary amylase – breaks down starch which is a complex molecule to sugar. - Pepsin – Helps to digest proteins in stomach. - Trypsin – It helps in digesting proteins to amino acids. - Lipase – Breaking down of emulsified fats to fatty acids and glycerol.
Important · 3 marks
14. Water is used by the leaves of the plants for photosynthesis but rather than watering the leaves, we water the plant through the soil. How does this water reach the leaves of the plant?
● In plants, the water is absorbed by the plants from the soil through the roots. Xylem tissue of the roots, stems and leaves are interconnected to form a continuous system of water conducting channels. ● During the day, when stomata are open, the transpiration pull becomes the major driving force for the movement of water in the xylem. ● Evaporation of water molecules from the stomata creates a suction which pulls water from the xylem cells of roots to the stem and then to the leaves.
Practice · 1 marks
15. Select the group in which all organisms have the same mode of nutrition. A. Cuscuta, yeast, legumes, leeches and tapeworm B. Cactus, ticks, lice, leeches and cow C. Cuscuta, ticks, lice, leeches and tapeworm D. Cactus, grass, lice, lion and tapeworm
C. Cuscuta, ticks, lice, leeches and tapeworm; as all of these are parasites.
Practice · 1 marks
16. Which of the following options indicates the products formed after breakdown of the glucose in our muscle cells when there is lack of oxygen? A. Ethanol + carbon dioxide + Energy B. Lactic acid + Energy C. Lactic acid + carbon monoxide + Energy D. Carbon dioxide + Water + Energy
B. Lactic acid + Energy
Important · 2 marks
17. Unlike animals, plants do not have any excretory products as they do not eat food. Comment upon the statement with justification.
It is completely wrong to say that plants do not produce any excretory products. However, plants use completely different strategies for excretion than those of the animals. They get rid of these wastes in different manner (any two): i. Oxygen, a photosynthetic waste, is removed through stomata. ii. Excess water is removed by transpiration through stomata. iii. Other metabolic wastes are either stored in dead cells, resins and gums or are removed through falling of old leaves. iv. Many waste products are stored in cellular vacuoles
Important · 2 marks
18. A. How many chambers are there in the heart of the following organisms? How is mixing of oxygenated and deoxygenated blood prevented in their body? (i) Fishes (ii) Humans OR B. Explain the mechanism by which the water is transported in plants?
A. (i) There are two chambers in the heart of fish. The blood is pumped to the gills, is oxygenated there and passes directly to the rest of the body. (ii) There are four chambers in the heart of a human being. Separation of the right side and the left side of the heart by septum prevents mixing of oxygenated and de-oxygenated bloods OR B. Xylem moves water and minerals obtained from the soil through roots to all other parts of the plant in a unidirectional manner// Transpiration takes place from leaf which causes a transpirational pull in the tracheids and vessels of xylem facilitating upward movement of water// roots actively uptake ions from the soil, leading to difference in concentration gradient, thereby water moves into the roots to eliminate this difference/ creating a steady movement of water into root xylem.
Practice · 1 marks
19. During photosynthesis, what happens to carbon dioxide and water as glucose is formed? A. Carbon dioxide gains hydrogen, while water loses electrons. B. Carbon dioxide loses oxygen, while water gains oxygen. C. Carbon dioxide is oxidised, while water is reduced. D. Both carbon dioxide and water undergo reduction.
A. Carbon dioxide gains hydrogen, while water loses electrons.
Practice · 1 marks
20. Which of the following statement is incorrect concerning the experiment to show that sunlight is necessary for photosynthesis? A. The leaf should be destarched before conducting the experiment. B. The leaf kept in darkness will show the presence of starch. C. The leaf exposed to sunlight will show the presence of starch. D. Starch is the end product of photosynthesis.
B. The leaf kept in darkness will show the presence of starch
Practice · 1 marks
21. During urine formation, tubular reabsorption and secretion take place in the kidneys. Which of the following sets correctly indicates both the substances that are reabsorbed in the kidneys? A. Glucose and salts B. Glucose and starch C. Glycogen and salts D. Glycogen and starch
A. Glucose and salts
Practice · 1 marks
22. Assertion (A): The rate of breathing in aquatic organisms is much lower than in the terrestrial organisms. Reason (R): The amount of oxygen dissolved in water is less as compared to the amount of oxygen in air. A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.
D. A is false but R is true.
Important · 2 marks
23. A. Due to narrowing of the bile duct, the bile secretion from the liver to the small intestine was obstructed. How will the process of digestion be affected? B. How does the length of the intestine depend on the nature of food habit in different animals?
The Bile juice from the liver makes the food alkaline for the pancreatic enzymes to act. In addition, bile salts break down fats into smaller globules increasing the efficiency of enzyme action. If bile duct is obstructed, it can lead to improper digestion of fats. Herbivores eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tigers have a shorter small intestine.
Very Important · 5 marks
24. A. I. How many chambers are present in the hearts of birds and mammals and how are they able to maintain their body temperature? Give reason for your answer II. How many chambers are present in the heart of fishes, how does circulation of blood take place in them? OR B. I. Describe the process of inhalation and also mention how are the lungs designed in human beings to maximise the area for exchange of gases? II. If diffusion were to move oxygen in our body, it is estimated that it would take 3 years for a molecule of oxygen to get to our toes from our lungs then, how is oxygen delivered to all parts of our body?
I. Four chambers are present. The separation of the right side and the left side of the heart is useful to keep oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body. This is useful in animals that have high energy needs, such as birds and mammals, which constantly use energy to maintain their body temperature. II. Two chambered heart. The blood is pumped to the gills, is oxygenated there, and passes directly to the rest of the body. Thus, blood goes only once through the heart in the fish during one cycle of passage through the body. OR I. - Ribs get lifted - Diaphragm is flattened, - The chest cavity becomes larger - Air is sucked in. The exchange of gases can take place on the surface, which is provided by the alveoli. The walls of the alveoli are supplied with an extensive network of blood vessels. - So lungs maximize the area for a gaseous exchange through the presence of large numbers of alveoli which are richly supplied with blood. II. In human beings, the respiratory pigment haemoglobin has a very high affinity for oxygen. This pigment is present in the red blood corpuscles. This oxygen-rich blood is then pumped by the heart to the rest of the body.
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