CBSE Class 10 Science Life Processes

MCQ Questions for NCERT Class 10 Science Life Processes

Question. As compared to terrestrial organisms, the rate of breathing in aquatic organisms is       
(a) slightly slower
(b) much faster
(c) almost the same
(d) much slower

Answer : B

Question. Which of the following parts is the site of the complete digestion of carbohydrates, proteins and fats?        
(a) Oesophagus
(b) Stomach
(c) Small intestine
(d) Large intestine

Answer : C

Question. Pyruvate is not a
(a) 6-carbon molecule
(b) 3-carbon molecule
(c) 4-carbon molecule
(d) 5-carbon molecule

Answer : C

Question. The amount of energy released after aerobic respiration is       
(a) less than that after anaerobic respiration
(b) much more than that after anaerobic respiration
(c) almost equal to that after anaerobic respiration
(d) about half of that after anaerobic respiration

Answer : B

Question. The inner lining of the small intestine has numerous finger-like projections called         
(a) jejunum
(b) duodenum
(c) ileum
(d) villi

Answer : D

Question. Water used in photosynthesis by terrestrial plants is taken up from         
(a) air
(b) soil
(c) either from air or from soil
(d) none of the above

Answer : B

Question. As compared to CO2, carbon monoxide binds to haemoglobin       
(a) loosely
(b) very strongly
(c) either loosely or strongly
(d) without any force

Answer : B

Fill in the blanks.

Question. Glucose is completely oxidized into CO H O 2 2 , and energy during ...... .
Answer : aerobic respiration

Question. In plants, respiration occurs at a much ...... rate than in animals.
Answer : slower

Question. Bile is yellowish ...... juice.
Answer : alkaline

Question. Pancreatic juice contains ...... for the breakdown of fat.
Answer : lipase

Question. Herbivores have longer small intestine to digest ...... .
Answer : cellulose

Question. The first step of aerobic respiration takes place in ......, while the second step takes place in the ...... .
Answer : cytoplasm, mitochondria

Question. Accumulation of excess ...... in the muscles causes pain.
Answer : lactic acid

Write Yes/No.

Question. Does gall bladder store pepsin?
Answer : No

Question. Do different parts of the plant respire independently?
Answer : Yes

Question. Do plants exchange gases through stomata?
Answer : Yes

Question. Are autotrophs dependent upon heterotrophs for their food requirements?
Answer : No

Question. Are the balloon-like structures present in our lungs called alveoli?
Answer : Yes

Important Questions for NCERT Class 10 Science Life Processes

Very-Short-Answer Questions

Question. Do the hair present inside our nose play any role?
Answer : They filter the air entering our nose.

Question. Why are cartilage rings present inside trachea?
Answer : So that the walls of the trachea do not collapse

Question. Name the structures through which food reaches the stomach from our mouth.
Answer : Pharynx and oesophagus

Question. Which is the longest part of the alimentary canal?
Answer : Small intestine

Question. How are bronchi formed?
Answer : Trachea branches out to form bronchi.

Question. Name the organelle where photosynthesis takes place.
Answer : Chloroplast

Question. Name the structures formed by the division of bronchioles.
Answer : Bronchioles divide to form alveolar duct.

Question. Differentiate between translocation and transpiration
Answer : Transpiration: loss of water from the leaves of plant Translocation: Transport of food from leaves to all parts of plants

Question. Describe the working of human blood circulatory system with the help of a suitable diagram which shows all steps involved.
Answer : Pulmonary and systemic circulation

Short-Answer Questions

Question. (a) How does carbon dioxide from the air enter the leaves of a plant to be used in photosynthesis?
(b) How does water from the soil reach the leaves of a plant to be used in photosynthesis?
Answer : (a) The carbon dioxide gas enters the leaves of the plants through the stomata present on their surface.
(b) The water required by the plants for photosynthesis is absorbed by the roots of the plants from the soil through the process of osmosis. The absorbed water is then transported upward through the xylem vessels to the leaves where it reaches the photosynthetic cells and utilized in photosynthesis.

Question. (a) Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long? Give reasons for your answer.
(b) What will happen to the rate of photosynthesis in a plant under the following circumstances?
(i) cloudy day in morning but bright sunshine in the afternoon.
(ii) no rainfall in the area for a considerable time.
(iii) gathering of dust on the leaves.
Answer : (a) This plant will not remain healthy for long because vaseline coating closes the stomatal pores on the leaves due to which (i) plant will not get oxygen for respiration (ii) plant will not get carbon dioxide for photosynthesis, and (iii) plant will not get water (and minerals) due to stoppage of transpiration.
(b) (i) Decreases in morning but increases in the afternoon
(ii) Decreases.
(iii) Decreases.

Question. (a) What is the common for cuscuta, ticks and leeches?
(b) Name the substances on which the following enzymes act in the human digestive system:
(i) Trypsin (ii) Amylase (iii) Pepsin (iv) Lipase
(c) Why does absorption of digested food occur mainly in the small intestine?
Answer : (a) Parasitic mode of nutrition.
(b) (i) Proteins (ii) Starch (iii) Proteins (iv) Fats.
(c) Absorption of digested foods occurs mainly in the small intestine due to the presence of a large number of finger like projections called villi.

Question. How do guard cells regulate opening and closing of stomatal pores?
(b) Two similar green plants are kept separately in oxygen free containers, one in dark and the other in continuous light. Which one will live longer? Give reasons.
Answer : (a) The opening and closing of stomatal pores is controlled by the guard cells, when water flows into the guard cells, they swell, become curved and cause the pore to open whereas when the guard cells lose water, they shrink, become straight and close the stomatal pore.
(b) Plant kept in continuous light will live longer because it will be able to produce oxygen required for its respiration by the process of photosynthesis.

Question. (a) “The breathing cycle is rhythmic whereas exchange of gases is a continuous process”. Justify this statement.
(b) What happens if conducting tubes of circulatory system develops a leak? State in brief, how could this be avoided?
(c) How opening and closing of stomata takes place?
Answer : (a) The breathing cycle involves inhalation and exhalation of air due to alternate expansion and contraction of thoracic cavity. Thus it is a rhythmic process. But exchange of gases is a continuous process as it takes place between the blood and each and every cell, by diffusion.
(b) The circulatory system will become inefficient if it develops a leak. This could be avoided by maintaining a normal blood pressure.
(c) When water flows into the guard cells, the guard cells swell and the stomatal pore opens up. When water moves out the guard cells shrinks and the stomatal pore closes

Question. (a) Describe the parts of our tooth with the help of a labelled diagram.
(b) What is meant by dental caries? How are they caused?
(c)What is dental plaque? What harm can it do? How can the formation of plaque be prevented?
Answer : (a) The tooth has hard outer covering called enamel. The part of tooth below enamel is called dentine inside which is the pulp cavity. The pulp cavity contains nerves and blood vessels.

(b) The formation of small cavities (or holes) in the teeth due to the action of acid forming bacteria and improper dental care is called dental caries.
This happens as follows: When we eat sugary food, the bacteria in our mouth act on sugar to produce acids. These acids dissolve the calcium salts from the tooth enamel and then from dentine forming small cavities in the tooth over a period of time in our mouth act on sugar to produce acids.
These acids dissolve the calcium salts from the tooth enamel and then from dentine forming small cavities in the tooth over a period of time.
(c) If the teeth are not cleaned regularly, they become covered with the sticky, yellowish layer of food particles and bacteria cells called dental plaque. It causes tooth decay. It can be prevented by brushing the teeth regularly as it neutralises the acids.

Question. (a) Name the main organs of the human digestive system. Also name the associated glands.
(b) How do carbohydrates, fats and proteins get digested in human beings?
Answer : a. The various organs of the human digestive system are mouth, oesophagus, stomach, small intestine and large intestine. The glands associated with the human digestive system are salivary glands, liver and pancreas.
b. (i) Carbohydrates - The digestion of carbohydrates begins in the mouth. The human saliva contains an enzyme called salivary amylase which digests the starch present in the food into maltose sugar. Pancreatic amylase present in the pancreatic juice breaks down the starch.
The intestinal juice of the small intestine completes the digestion of carbohydrates and finally coverts it into glucose.
(ii) Fats - The process of digestion of fats begins in the stomach. The glands of stomach secrete a small amount of gastric lipase that breaks down the fats present in the food. From the stomach the partially digested food goes into small intestine where the pancreatic lipase breaks down the emulsified fats. The walls of small intestine secrete intestinal juice which converts the fats into fatty acids and glycerol.
(iii) Proteins - The digestion of proteins begins in the stomach. The glands of the stomach secrete gastric juice which contains an enzyme called pepsin. Pepsin converts the proteins into peptones. Pancreatic juice contains trypsin which digests the proteins into peptides and the intestinal juice completes the process of digestion of proteins thus converting it into amino acids.

Question. Draw a schematic representation of transport and exchange of oxygen and carbon dioxide during transportation of blood in human beings and label on it:
Lung capillaries, Pulmonary artery to lungs, Aorta to body, Pulmonary veins from lungs.
(b) What is the advantage of separate channels in mammals and birds for oxygenated and deoxygenated blood?
Answer : (a) A schematic representation of transportation and exchange of oxygen and carbon dioxide during transportation of blood in human beings

(b) It is necessary to separate oxygenated and deoxygenated blood in mammals and birds because they need high energy and large amount of oxygen. The separation of oxygenated and deoxygenated blood provides high oxygen supply to the organs.

Question. Explain how, the air we breathe in gets cleaned while passing through the nasal passage.
(b) Why do the walls of trachea not collapse when there is less air in it?
(c)How are oxygen and carbon dioxide exchanged in our body during respiration?
(d) How are lungs designed in human beings to maximise the exchange of gases?
Answer : (a) When air passes through the nasal passage, the dust particles and other impurities present in it are trapped by nasal hair and mucus so that clean air goes into the lungs.
c. Trachea does not collapse even when there is no air in it because it is supported by rings of soft bones called cartilage.
d. During the process of 'breathing in' the air sacs or alveoli of the lungs get filled with air containing oxygen. The alveoli are surrounded by capillaries carrying blood so the oxygen of air diffuses from the alveoli walls into the blood from where it is carried to all the parts of the body.
As the blood passes through the tissues of the body, the oxygen present in it diffuses into the cells. This oxygen combines with the digested food to release energy. Carbon dioxide gas is produced as a waste product during respiration in the cells of the body tissues which diffuses into the blood. Blood carries the carbon dioxide back to the lungs where it diffuses into the alveoli.
e. The human lungs have been designed to maximise the exchange of gases as there are millions of alveoli in the lungs which provides a large surface area for the exchange of gases.

LIFE PROCESSES

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