CBSE Class 10 Science Life Processes Assignment Set C

Question. Choose the correct statement(s) amongst the following.       
(a) For regulating different life processes energy is required.
(b) Living organisms grow with time.
(c) Living organisms need to repair and maintain their structures.
(d) Molecules within the cells do not exhibit movement.
Answer : B

Question. Identify the correct path of urine in the human body.
(a) Kidney → urinary bladder → urethra → ureter
(b) Urinary bladder → ureter → kidney → urethra
(c) Kidney → ureter → urethra → urinary bladder
(d) Kidney → ureter → urinary bladder → urethra
Answer : D

Question. Coagulation of blood in a cut or wound is brought about by:
(a) plasma
(b) platelets
(c) WBC
(d) RBC
Answer : B

Question. The opening and closing of the stomatal pore depends upon
(a) Oxygen
(b) Temperature
(c) water in the guard cells
(d) concentration of CO₂
Answer : C

Question. Name the substances whose build up in the muscles during vigorous physical exercise may cause cramps?
(a) Ethanol + Carbon dioxide + Energy
(b) Lactic acid + Energy
(c) Carbon dioxide + Water + Energy
(d) Pyruvate
Answer : B

Question. The food in autotrophs is reserved in the form of       
(a) protein
(b) fatty acid
(c) glycogen
(d) starch
Answer : D

Question. Which of the following respiratory structures has cartilage rings to prevent it from collapsing?       
(a) Nasal cavity
(b) Pharynx
(c) Larynx
(d) Trachea
Answer : D

Question. Which of the following is the correct sequence representing human alimentary canal?    
(a) Mouth → oesophagus → stomach → small intestine → large intestine
(b) Mouth → small intestine → stomach → oesophagus → large intestine
(c) Mouth → stomach → oesophagus → small intestine → large intestine
(d) Mouth → stomach → oesophagus → large intestine → small intestine
Answer : A

Question. Pancreatic juice is carried by the pancreatic duct into              
(a) large intestine 
(b) liver
(c) duodenum
(d) stomach
Answer : C

Question. Which part of human cell is involved in conversion of pyruvic acid into lactic acid during deficiency of oxygen?       
(a) Golgi body
(b) Mitochondria
(c) Cytoplasm
(d) Lysosome
Answer : C

Question. Which of the following gases turns lime water milky when we blow air into it from mouth?       
(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Carbon monoxide
Answer : B

Question. Which of the following processes is responsible for cramps in the muscles of sportsmen?       
(a) Nonconversion of glucose to pyruvate
(b) Conversion of pyruvate to lactic acid due to deficiency of oxygen
(c) Conversion of pyruvate to glucose in presence of oxygen
(d) Conversion of pyruvate to ethanol
Answer : B

Question. What role is played by stomata during photosynthesis?
Answer : CO₂ enters the leaves and O₂ is released into air through stomata.

Question. Where is bile stored?
Answer : Gall bladder

Question. Name the organism which converts pyruvate to ethanol.
Answer : Yeast

Question. Where does the second stage of aerobic respiration take place?
Answer : Mitochondria

Question. Which type of organ is vermiform appendix?
Answer : Vestigial

Question. From where does a plant obtain water for photosynthesis?
Answer : Water is absorbed from soil.

Question. What is similar among animals, fungi and some bacteria?
Answer : They cannot prepare their own food.

Question : Why is transpiration important for plants?
Answer : Transpiration is important because:
(1) it helps in absorption and upward movement of water and minerals from roots to leaves.
(2) it prevents the plant parts from heating up.

Question :  What is mode of nutrition in fungi? 
Answer : In fungi, there is saprotrophic mode of nutrition. In this case organisms obtain foodfrom dead and decaying organic matter.

Question :  How does water reach upto the leaves ? 
Answer : Water is taken up by the roots and reaches the leaves through the xylem vessels which are a part of the vascular bundle.

Question :  While eating you are advised not to talk. Why are you advised so? 
Answer : We are advised so because while eating some food particles might enter the wind pipe which can lead to choking.

Question : In the experiment set up to show that “CO₂ is given out during respiration”, name the substance taken in the small test tube kept in the conical flask. State its function and the consequence of its use. 
Answer : The substance taken in a small test tube in the conical flask is Potassium Hydroxide or KOH. The KOH solution absorbs the evolved carbon dioxide released by germinating seeds during respiration. The absorption of all the released CO2 gas by KOH solution creates a partial vacuum in the conical flask due to which level of water rises up in the tube.

Question : Define parasitic nutrition. Name an organism having parasitic mode of nutrition.
Answer : Parasitic Nutrition: The parasitic nutrition is that nutrition in which an organism derives its food from the body of another living organism without killing it. Organisms having parasitic mode of nutrition are Plasmodium and round-worms.

Question : In which form do plants store the carbohydrates which are not used immediately?
Answer : Plants store carbohydrates which are not used immediately in the form of starch.

Question : How is the opening and closing of stomatal pore regulated in plants?
Answer : The opening and closing of stomatal pores is a function of guard cells. When water flows into guard cells, they swell up causing the stomatal pore to open. When the guard cells shrink, the pore closes.

Question : If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer. 
Answer : If the plant shows evidence that it is releasing CO2 during the day and taking in oxygen, it does not mean that there is no photosynthesis taking place in the plant. Instead, it suggests that the plant is undergoing photosynthesis at a very low rate. In a normal scenario, the rate of respiration is higher during night while it is slower during the day. The CO₂ produced during night time is utilized by the plant during the day to perform photosynthesis. 

Short Answer

Question : What is photosynthesis? Explain its mechanism.
Answer : Photosynthesis– A process in which green plants takes carbon dioxide and water and converts them into carbohydrates in the presence of sunlight and chlorophyll.

Mechanism:
(i)Absorption of light energy by chlorophyll.
(ii)Conversion of light energy to chemical energy.
(iii)Splitting of water molecules (H₂O) into hydrogen and oxygen.
(iv)Reduction of carbon dioxide to carbohydrate.

Long Answer

Question : Answer the following:
(A) What would happen if all the green plants disappear from the earth?
(B) If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? justify your answer.
Answer :  (A) Green plants are the sources of energy for all organisms. If all green plants disappear from the earth, all the herbivore will die due to starvation and so will the carnivores.
Since autotrophs are the only organisms that can fix the atmospheric carbon dioxide into organic compounds, these organisms occupies first trophic level in food chain and serve as source of food and energy for all other organisms of higher trophic evels (heterotrophs/consumers). Hence, in absence of these plants, whole functioning of whole ecosystem will come to a halt due to lack of food and energy source for consumers (herbivores, carnivores and omnivores)
(B) Respiration is the process of oxidation of food substances that release carbon dioxide; it takes place throughout the day. Photosynthesis is the process of fixing the atmospheric carbon dioxide into organic compounds (carbohydrates) with release of oxygen gas as by product. Photosynthesis takes place during the day in presence of Sunlight only.
The CO₂ released during respiration is absorbed by plants for photosynthesis during day causing net release of oxygen only. If a plant is releasing carbon dioxide and taking in oxygen during the day, it means that either rate of photosynthesis is too slow to counter balance the release of CO₂ by respiration or photosynthesis is not taking place at all.