CBSE Class 10 Science HOTs Question Life Processes

Multiple Choice Question

Question. Which of the following statements are true about autotrophs?           
(a) They convert carbon dioxide and water into carbohydrates in presence of light.
(b) They store carbohydrates in the form of starch.
(c) They occupy second trophic level in food chains.
(d) They are chlorophyll-bearing organisms.

Answer : A

Question. In human body, food is finally digested in           
(a) large intestine
(b) small intestine
(c) stomach
(d) oesophagus

Answer : B

Question. Which of the following events takes place during photosynthesis?           
(a) Trapping of light energy by chlorophyll molecules
(b) Conversion of light energy to chemical energy
(c) Reduction of CO2 to carbohydrates
(d) Release of CO2 in the atmosphere

Answer : A

Question. The muscular and tubular part of the alimentary canal is called       
(a) pharynx
(b) small intestine
(c) oesophagus
(d) stomach

Answer : C

Question. Which of the following functions is carried out by pancreatic juice?       
(a) Lipase emulsifies fats and trypsin digests proteins.
(b) Lipase digests carbohydrates and trypsin digests fats.
(c) Lipase emulsifies both carbohydrates and fats.
(d) Trypsin digests both proteins and fats.

Answer : A

Question. In which of the following groups of organisms food material is broken down outside the body?           
(a) Cuscuta, Amoeba, green plants
(b) Amoeba, Paramoecium, Cuscuta
(c) Yeast, green plants, mushroom
(d) Mushroom, bread mould, yeast

Answer : D

Question. Which of the following protects the inner lining of stomach from hydrochloric acid?           
(a) Mucus
(b) Bile
(c) Pepsin
(d) Amylase

Answer : A

Question. Select the incorrect statement(s).    
(a) Heterotrophs contain chlorophyll pigments.
(b) Heterotrophs can convert solar energy to chemical energy.
(c) Heterotrophs are unable to synthesize food.
(d) Heterotrophs occupy first trophic level in food chain.

Answer : A

Question. During photosynthesis oxygen is evolved from        
(a) CO2
(b) water
(c) glucose
(d) chlorophyll

Answer : B

Question. Which of the following statement(s) is/are correct?    
(a) Fermentation is a form of aerobic respiration.
(b) Aerobic respiration involves mitochondria.
(c) Lactic acid is formed in human muscle cells during anaerobic respiration.
(d) Pyruvate can be converted into ethanol in mitochondria.

Answer : B

Question. The part of the digestive system where no digestion takes place is
(a) ileum
(b) stomach
(c) mouth
(d) oesophagus

Answer : D

Question. The procedure used for cleaning the blood of a person by separating urea from it is called:
(a) osmosis
(b) filtration
(c) dialysis
(d) double circulation

Answer : C

Question. Which plant tissue transports water and min-erals from the roots to the leaf?
(a) Xylem
(b) Phloem
(c) Parenchyma
(d) Collenchyma

Answer : A

Question. The filtration units of kidneys are called 
(a) ureter
(b) urethra
(c) neurons
(d) nephrons

Answer : D

Question. A blood vessel which pumps the blood from the heart to the entire body:
(a) artery
(b) capillary
(c) Vein
(d) Haemoglobin

Answer : A

Question. The fermentation of glucose by yeast normally yields
(a) alcohol, CO₂ and 36 ATP
(b) CO₂, H₂0 and 36 ATP
(c) alcohol, CO₂ and 2ATP
(d) lactic acid, CO₇ and 2 ATP

Answer : D

Question. Normal blood pressure (systolic/diastolic) is
(a) 120/80 mm of Hg
(b) 160/80 mm of Hg
(c) 120/60 mm of Hg
(d) 180/80 mm of Hg

Answer : A

Question. Roots of the plants absorb water from the soil through the process of:
(a) diffusion
(b) transpiration
(c) osmosis
(d) None of these

Answer : C

Question. Autotrophic organisms include
(a) bacteria and virus
(b) bacteria and fungi
(c) green plants and some bacteria
(d) green plants and all bacteria

Answer : C

Question. From the given picture of the digestive system, identify the part labelled as gastric gland.
(a) A
(b) B
(c) C
(d) D

Answer : B

Question. Blood pressure is measured by an instrument called
(a) barometer
(b) sphygmomanometer
(c) photometer
(d) manometer

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. The mode of nutrition found in fungi is:
(a) Parasitic nutrition
(b) Holozoic nutrition
(c) Autotrophic nutrition
(d) Saprotrophic nutrition

Answer : D

Question. When air is blown from mouth into a test-tube containing lime water, the lime water turns milky due to the presence of 
(a) oxygen
(b) carbon dioxide
(c) nitrogen
(d) water vapour

Answer : B

Question. Oxygen liberated during photosynthesis comes from 
(a) water
(b) chlorophyll
(c) carbon dioxide
(d) glucose

Answer : A

Question. A large quantity of one of the following is removed from our body by lungs:
(a) CO₂ and H₂0
(b) CO₂ only
(c) FLO only
(d) ammonia

Answer : A

Question. Which part of alimentary canal receives bile from the liver? 
(a) Stomach
(b) Small intestine
(c) Large intestine
(d) Oesophagus

Answer : B

Question. The opening and closing of the stomatal pore depends upon
(a) oxygen
(b) temperature
(c) water in guard cells
(d) concentration of CO₂ in stomata

Answer : C

Question. In amoeba, food is digested in the:
(a) food vacuole
(b) mitochondria
(c) pseudopodia
(d) chloroplast

Answer : A

Question. In respiration, air passes through
(a) Pharynx → nasal cavity → larynx → trachea bronchi → bronchioles
(b) Nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles
(c) Larynx → nasal cavity’ → pharynx → trachea
(d) Larynx → pharynx trachea → lungs

Answer : B

Fill in the blanks.

Question. Nutrition provides ...... to the body.
Answer : nutrients

Question. Pyruvate may be converted into ethanol and CO2 during ...... .
Answer : fermentation

Question. ...... pairs of salivary glands are present in human mouth.
Answer : Three

Question. The opening and closing of stomata is regulated by ...... .
Answer : guard cells

Question. Heterotrophic organisms obtain food from ...... organisms.
Answer : other

Write Yes/No.

Question. Is Cuscuta a parasitic plant?
Answer : Yes

Question. Does food mix thoroughly with saliva in our mouth when we chew properly?
Answer : Yes

Question. Are carbohydrates stored in the form of starch in plants?
Answer : Yes

Question. Is it true that light energy is not directly absorbed by chlorophyll molecules?
Answer : No

Question. Does our chest cavity become smaller when we breathe in?
Answer : No

True (T) or False (F).

Question. Carbon monoxide binds more strongly to haemoglobin than oxygen.
Answer : true 

Question. All alveoli are not covered by web of blood capillaries.
Answer : false

Question. Carbon and energy requirements of the autotrophic organisms are fulfilled by photosynthesis.
Answer : true 

Question. Oxygen is released during photosynthesis.
Answer : true 

Question. CO2 is not essential for photosynthesis.
Answer : false

Question Answer

Question. Due to availability of less water, how does the plant cope up with lack of water in desert conditions?
Answer : They open their stomata at night and stomata remain closed during day time, to conserve moisture.

Question. After a vigorous exercise, you may experience cramps in your leg muscles. Why does this happen?
Answer : The sudden build up of lactic acid in our muscles during vigorous, exercise, causes muscular cramps in our leg muscles.

Question. What will happen if carbon monoxide combines with haemoglobin?
Answer : If the haemoglobin binds with carbon monoxide strongly, the oxygen will not be carried with blood leading to death of the organism.

Question. Food moves down the gut by peristalsis. Which region of brain controls peristalsis?
Answer : Medulla of hind brain

Question. Name the pigment present in plants, which can absorb solar energy.
Answer : Chlorophyll.

Question. Name the respiratory organs of (i) fish (ii) mosquito (iii) earthworm.
Answer : Fish - gills
Mosquito – Trachea (air tubes)
Earthworm – moist skin

Question. Which of the four chambers of the human heart has the thickest muscular walls?
Answer : Right ventricle.

Question. What will be the outcome if a farmer floods his field everyday?
Answer : Respiration of plants will be affected because the oxygen present in the interspaces of the soil will be replaced by water.

Question. Which part of visible spectrum is absorbed by chlorophyll pigments?
Answer : Blue and Red light

Question. How does respiration in plants differ from that in animals?
Answer : In plants, all parts like the root, stem, leaves, etc., perform respiration individually., while in animals, either the general body surface or specific organs like the skin, gills, lungs, etc., are involved in respiration. The rate of respiration is much slower in plants than in animals. Unlike animals, there is little transport of gases from one part of the plant to another.

Question. Name the cartilaginous flap which closes the glottis to check the entry of food into it during swallowing.
Answer : Epiglottis

Question. Which equipment is used to facilitate breathing during serious breathing problems?
Answer : Ventilator

Question. Chloroplast are called energy convertors. Explain.
Answer : Chloroplasts are called energy convertors because they trap the solar energy and convert it into chemical energy.

Question. Why is the rate if breathing much faster in aquatic organisms than those of terrestrial organisms?
Answer : The aquatic organisms obtain oxygen dissolved in water. As compared to air, the availability of oxygen in water is fairly low. Hence, the aquatic organisms have to breathe faster as compared to the terrestrial organisms.

Question. Why are glomeruli considered as dialysis bags?
Answer : The main function performed by the glomeruli is selective filtration. They filter small molecules containing glucose, salts, urea, and liquid serum. Etc. The large molecules such as proteins remain in blood. Thus, glomeruli of the kidneys function as dialysis bags.

Question. Autotrophs synthesise food for the living world. Justify this statement in one sentence only interconnecting autotrophs and heterotrophs.
Answer : The food producers are autotrophs and all the heterotrophs consume the food produced by the autotrophs directly or indirectly.

Question. Veins and arteries carry blood. Which of these carry blood?
a) Away from the heart?
b) Back to the heart?
Answer : a) Arteries carry blood away from the heart.
b) Veins carry blood back to the heart.

Question. Which of the organs perform the following functions in humans?
1. Absorption of food.
2. Absorption of water
Answer : 1. Absorption of food takes place in small intestine.
2. Large intestine

Question. Name the areas in a woody stem through which respiratory exchange of gases take place.
Answer : In woody stem, the bark has lenticels for gaseous exchange.

Question. Tooth enamel is one of the hardest substances in our body. How does it undergo damage due to eating chocolates and sweets?
Answer : The acid is formed in the mouth after a sugary food (chocolates and sweet) has been taken. This acid lowers the pH in the mouth. Tooth decay starts when the pH of acid formed in the mouth falls below 5.5. This is because then the acid becomes strong enough to attack the enamel of our teeth and corrode it.

Question. A certain tissue in a green plant somehow get blocked and the leaves wilted. What was the tissue that got blocked?
Answer : The tissue that got blocked may be xylem. It is through the xylem that water and minerals absorbed by roots from the soil are transported to the leaves and other parts of the plant. So, if xylem is blocked, the leaves will not get the nourishment and will get wilted.

Question. Write one feature which is common to each of the following pairs of the term/organs.
i) glycogen and starch ii) chlorophyll and haemoglobin
iii) gills and lungs iv) arteries and veins.
Answer : i) Carbohydrate (food)
             ii) Pigments.
             iii) Respiratory organs.
             iv) Blood vessels.

Question. Why doesn’t the lungs collapse even after forceful expiration?
Answer : Even after forceful expiration to the maximum capacity, some amount of air remains in the lungs, known as residual volume. So, the lungs doesn’t collapse even after forceful expiration.

Question. The two openings of the pharynx, one leading to trachea and the other leading to oesophagus, lie very close to each other. Yet food we swallow normally does not enter into our trachea. Why?
Answer : The food does not enter into trachea because during swallowing, the aperture leading to trachea (glottis) gets covered by a cartilaginous flap called epiglottis and the food has no other passage except going into the oesophagus.

Question. How would it affect the digestion of proteins and carbohydrates if the duodenum of man if there is a blockade in the pancreatic duct?
Answer : Duodenum is the region where the pancreatic juice secreted by the pancreas enters. The enzymes pancreatic amylase and trypsin helps in the digestion of carbohydrates and proteins. Thus, if there is a blockade, the digestion of carbohydrates and proteins gets affected.

Question. What do you mean by double circulation of blood?
Answer : Blood passes through the heart twice for each cycle of the body.

Question. “If there were no algae there would be no fish in the sea”. Comment.
Answer : Algae produce O2 as a result of photosynthesis. This oxygen is utilised by the fishes in the sea for carrying out respiration. If there were no algae, no oxygen would have been produced. Thus, fishes might have died.

Question. Write the functions of the following in the digestive process:
(i) Bile
(ii) Bicarbonate secreted by the duodenal wall.
(iii) Pancreatic amylase.
Answer : 1. Bile: It is secreted by the gall bladder and it emulsifies the fats into the smaller droplets for their easy digestion.
               2. It provides alkaline medium in the duodenum which is needed for the action of pancreatic enzymes of different food components for their digestion.
               3. Pancreatic amylase enzyme digests starch and changes it into maltose.

Question. Why is the process of diffusion insufficient to meet the oxygen requirement of human beings?
Answer : The process of diffusion for carrying O2 to all parts of the body is not sufficient for larger multicellular organisms like human beings. Hence, respiratory pigment haemoglobin takes up oxygen from the air and carry it to all the parts of our body through blood.

Question. Draw a diagram of human alimentary canal showing duodenum, small intestine, liver and pancreas.
Answer : Textbook Page No. 99, Figure 6.6 

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. We say that movement is a characteristic of living organisms but we always don’t see visible movements in plants. Comment. 1 Mark
Answer : We always don’t see visible movements in plants. It does not mean that they are not alive. Molecular movements take place in their body.

Question. If a person is working on a treadmill in a gymnasium, will it effect his rate of breathing? How? 
Answer : Yes, it will affect his rate of breathing. The rate of breathing will become fast to supply more oxygen to meet the increased demand of energy.

Question. If you compare your rate of breathing by feeling your chest movement with the number of times a fish opens and closes its mouth. Which will be higher and why? 2 Marks
Answer : The number of times a fish opens and closes its mouth will be higher as the amount of dissolved oxygen in water is fairly low compared to the amount of oxygen in the air. Therefore, rate of breathing in aquatic organisms is much faster than in terrestrial organisms.

Question. Mucus is not used for churning the food or digesting it. Then why is it secreted in the stomach? 
Answer : Mucus is secreted in the stomach to protect its inner lining from being damaged by HCl. Excessive secretion of HCl can damage the lining and lead to peptic ulcer.

Question. In the process of Photosynthesis food A is prepared which gets converted into food B. What are A and B? Why is A converted to B? 2 Marks
Answer : Food A is glucose and food B is Starch.
A is converted to B as B is insoluble form of carbohydrate. It is more compact and hence, suitable for storage.

Question. When we are asleep we are not performing any activity still our life processes are going on. Why? 
Answer : “The maintenance functions of living organisms must go on even when they are not doing anything particular.” That is why the life processes are going on even while we are asleep or not performing any activity.

Question. Leaves of a healthy potted plant were coated with petroleum jelly. How will it affect the plant? State two reasons. 
Answer : The plant will not remain healthy for long due to the following reasons:-
1. There will be no transpiration.
2. There will be no exchange of gases which will affect the rate of photosynthesis.

Question. The wall of trachea is supported by cartilage rings. Give reasons.

Answer. The wall of trachea is supported by C shaped cartilage rings which does not allow the collapse of trachea when there is not much air in it.

Question. Write one feature which is common to each of the following pairs of terms/organs:

i) Glycogen and starch ii) Chlorophyll and hemoglobiniii) Gills and Lungs iv) Arteries and Veins

Answer. i)Glycogen and starch: Reserve food is in the form of glycogen in animal cell and starch in plant cell.

ii) Chlorophyll and hemoglobin: Both are pigments, chlorophyll is photosynthetic pigment while hemoglobin is respiratory pigment present in blood.

iii) Gills and Lungs: Both are organs meant for breathing, gills in fish and lungs in birds and mammals.

iv) Arteries and Veins: both are blood vessels, arteries carry blood from heart to different parts of the body while veins bring back blood from different parts of body towards heart.

Question. Why is the rate if breathing much faster in aquatic organisms than those of terrestrial organisms?

Answer.- The aquatic organisms obtain oxygen dissolved in water. As compared to air, the availability of oxygen in water is fairly low. Hence, the aquatic organisms have to breathe faster as compared to the terrestrial organisms

Question. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?

Answer.- They have high energy requirement for maintaining their body temperature. This is possible only if oxygenated and deoxygenated blood remain separated.

Question. Why does absorption of digested food occur mainly in the small intestine?

Answer. Maximum absorption occurs in small intestine because

i) Inner lining of small intestine is provided with villi which increases the surface area for absorption.

ii) Wall of intestine is richly supplied with blood vessels which take the absorbed food to each and every cell of the body.

Question. What are the methods used by plants to get rid of excretory products?

Answer. I) the oxygen which is produced during the process of photosynthesis gets removed through stomata.

ii) The carbon di oxide which is produced during process of respiration also gets removed through stomata.

iii) Excess of water gets removed through transpiration

iv) Some waste products are stored in cellular vacuoles.

v) Some waste products are stored as resins and gums especially in old xylem.

vi) Plants also excrete some waste substances into the soil around them.

vii) Some waste substances are also removed through petals, fruits and seeds.

Question. what will happen if carbon monoxide combines with hemoglobin?

Answer- If the hemoglobin binds with carbon monoxide strongly, the oxygen will not be carried with blood leading to death of the organism.

Question. A certain tissue in a green plant somehow get blocked and the leaves wilted. What was the tissue that got blocked?

Answer-The tissue that got blocked may be xylem. It is through the xylem that water and minerals absorbed by roots from the soil are transported to the leaves and other parts of the plant. So, if xylem is blocked, the leaves will not get the nourishment and will get wilted.

Question. Which organ secretes a hormone when the blood sugar rises? Name a digestive enzyme released by this organ and write down its function also.

Answer. The pancreas secretes a hormone insulin which regulates the blood sugar level. Digestive enzymes secreted by pancreas are trypsin and lipase, they helps in the digestion of proteins and fats respectively.

Question. Why is blood circulation in human heart called double circulation?

Answer. The blood passes through the heart twice in one complete cycle of the body. Once through the right heart in the form of deoxygenated blood and once through the left half in the form of oxygenated blood.

Question. What is common for cuscuta, ticks and leeches?
Answer. Cuscuta, ticks and leeches, all has parasitic mode of nutrition, they harm their host while taking nutrition.

Question. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?
Answer. Adaptation of terrestrial organism over aquatic organism for efficient uptake of oxygen from air –
(i) Increased respiratory surface area.
(ii) Very fine and delicate surface for easy exchange of oxygen and carbon – dioxide.
(iii) Placement of respiratory surface within the body for protection
(iv) Mechanism for moving the air in and out of respiratory surface where the oxygen is absorbed

Question. Name the substrates for the following enzymes
1. trypsin
2. amylase
3. pepsin
4. lipase

Answer. a) Protein
b) Starch
c) Protein
d) Lipids

Question. What are the two stages in photosynthesis?
Answer. Two stages in photosynthesis –
a) Light reaction – Light energy breaks up water molecular into hydrogen and oxygen, called photolysis of
water
b) Dark reaction – Fixation and conversion of carbon – dioxide (CO ) into a simple carbohydrates glucose.

Question. What is villi? What are its functions?
Answer. Finger like projection present in the inner lining of small intestine are called villi. They increase the surface area for the absorption of digested food in the small intestine.

Question. What type of respiration takes place in human muscles during vigorous exercise and why?
Answer. During vigorous exercise, anaerobic respiration takes place in human muscles. During exercise our energy requirement increase, so our striated muscles start respiring anaerobically in the lack of oxygen and producers ATP molecules.

Question. How is opening and closing of stomata regulated?
Answer. The closing and openings of the stomata is regulated by guard cells. When the guard cells swell or turgid due to entry of water, the stomata are opened. The guard cells shrink due to loss of water the stomata get closed.

Question. State two vital functions of kidney.
Answer. Function of kidney are –
1. It maintains water balance in the body tissues.
2. It controls calcium levels in the blood to maintain healthy bones.

Question. Meat is easier to digest as compared to grass. Why?
Answer. It is easier to digest meat because our digestive juices contain enzymes which can easily digest meat but our body does not digest cellulose which is a main component of grass.

Question. What is the role of glomerulus in kidney?
Answer. Glomerulus is a group of capillaries present in the cup like Bowman’s Capsule. It receives blood from renal artery which brings excretory wastes from body to the kidney. It filters water, salts, glucose, urea, the nitrogen containing end products of proteins and yellow bile compounds from the liver.

Question. Why is it essential to match the blood groups of donors and receiver person before arranging transfusion of blood?
Answer. RBC’s of blood carries antigen as well as antibody. If blood is not matched before transfusion then blood of receiver start producing antibodies against donor blood and destroys blood cells, this causes deficiency of blood and causes death.

Question. Why is it necessary to separate oxygenated & deoxygenated blood in mammals & birds?
Answer. Separation of oxygenated and deoxygenated blood allows good supply of oxygen to the body. This system is useful in animals that have high energy requirement Mammals and birds constantly need oxygen to get energy to maintain constant body temperature.

Question. Why the walls of trachea are supported by cartilaginous rings?
Answer. The trachea is supported by cartilaginous rings which prevent the collapsing even when there is not much air in it.

Question. What are the raw materials for photosynthesis?
Answer. Raw materials for photosynthesis are –
1. Carbon – dioxide
2. Water
3. Chlorophyll and Sunlight

Question. What is the role of diaphragm during inhalation and exhalation?
Answer. Diaphragm changes its shape during inhalation and exhalation and increases and decreases volume of thoracic cavity respectively. This causes entry and expel of air from lungs.

Question. What is the advantage of four chambered of heart?
Answer. The right and left parts are separated by a septum to prevent oxygenated and deoxygenated blood from mixing. This fulfills the constant use of energy to maintain their body temperature. Their energy needs are high, which are fulflled efficiently because of non – mixing of oxygenated & deoxygenated blood.

Question. Why is diffusion insuficient to meet the oxygen requirements of multicellular organisms like humans?
Answer. As in multicellular organisms, all the cells are not in direct contact with environment, simple diffusion does not meet the requirement of all the body cells.

Question. What criteria do we use to decide whether something is alive?
Answer. All the living organism must have movement at molecular levels along with respiration and other life process like nutrition, respiration, transportation and excretion to be called alive.

Question. What is the function of digestive enzymes?
Answer. Enzymes break-down the various complex components of food into simple and soluble components so that they can be absorbed easily.

Question. How are the lungs designed in human beings to maximize the area for exchange of gases?
Answer. In lungs, the bronchioles terminate in balloon-like structures called alveoli. The alveoli contain network of blood capillaries that increase the surface area for exchange of gases.

Question. What is the role of saliva in the digestion of food?
Answer. The saliva contains an enzyme called salivary amylase that breaks down starch which is complex molecule into glucose.

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. We say that movement is a characteristic of living organisms but we always don’t see visible movements in plants. Comment.
Answer. We always don’t see visible movements in plants. It does not mean that they are not alive. Molecular movements take place in their body.

Question. If a person is working on a treadmill in a gymnasium, will it effect his rate of breathing? How?
Answer. Yes, it will affect his rate of breathing. The rate of breathing will become fast to supply more oxygen to meet the increased demand of energy.

Question. If you compare your rate of breathing by feeling your chest movement with the number of times a flsh opens and closes its mouth. Which will be higher and way?
Answer. The number of times a flsh opens and closes its mouth will be higher as the amount of dissolved oxygen in water is fairly low compared to the amount of oxygen in the air. Therefore, rate of breathing in aquatic organisms is much faster than in terrestrial organisms.

Question. Mucus is not used for churning the food or digesting it. Then why is it secreted in the stomach?
Answer. Mucus is secreted in the stomach to protect its inner lining form being damaged by HCI. Excessive secretion of HCI can damage the lining and lead to peptic ulcer.

Question. In the process of Photosynthesis food A is prepared which gets converted into food B. What are A and B? Why is A converted to B?
Answer. Food A is glucose and food B is Starch.
A is converted to B as B is insoluble form of carbohydrate. It is more compact and hence, suitable for storage.

Question. When we are asleep we are not performing any activity still our life processes are going on. Why?
Answer. “The maintenance functions of living organisms must go on even when they are not doing anything particular.” That is why the life processes are going on even while we are asleep or not performing any activity.

Question. What will be the outcome if a farmer floods his field everyday?
Answer. Respiration of plants will be affected because the oxygen present in the interspaces of the soil will be replaced by water.

Question. Name the respiratory organs of (i) fish (ii) mosquito (iii) earthworm.
Answer. Fish – gills

Mosquito – Trachea (air tubes)
Earthworm – moist skin

Question. Due to availability of less water, how does the plant cope up with lack of water in desert conditions?
Answer. They open their stomata at night and stomata remain closed during day time, to conserve moisture.

Question. After a vigorous exercise, you may experience cramps in your leg muscles. Why does this happen?
Answer. The sudden build up of lactic acid in our muscles during vigorous, exercise, causes muscular cramps in our leg muscles.

Question. What will happen if carbon monoxide combines with hemoglobin?
Answer. If the hemoglobin binds with carbon monoxide strongly, the oxygen will not be carried with blood leading to death of the organism.

Question. Chloroplast are called energy convertors. Explain.
Answer. Chloroplasts are called energy convertors because they trap the solar energy and convert it into chemical energy.

Question. Why is the rate if breathing much faster in aquatic organisms than those of terrestrial organisms?
Answer. The aquatic organisms obtain oxygen dissolved in water. As compared to air, the availability of oxygen in water is fairly low. Hence, the aquatic organisms have to breathe faster as compared to the terrestrial organisms.

Question. Why are glomeruli considered as dialysis bags?
Answer. The main fimetion performed by the glomeruli is selective filltration. They filter small molecules containing glucose, salts, urea, and liquid senim. Etc. The large molecules such as proteins remain in blood. Thus, glomenili of the kidneys function as dialysis bags.

Question. Veins and arteries catty blood. Which of these carry blood?
1. Away from the heart?
2. Back to the heart?
Answer. a) Arteries carry blood away from the heart.
b) Veins carry blood back to the heart.

Question. Which of the organs perform the following functions in humans?
1. Absorption of food.
2. Absorption of water
Answer. i. Absorption of food takes place in small intestine.
ii. Large intestine

Question. Name the areas in a woody stem through which respiratory exchange of gases take place.
Answer. In woody stem, the bark has lenticels for gaseous exchange.

Question. Why doesn’t the lungs collapse even after forceful expiration?
Answer. Even after forceful expiration to the maximum capacity, some amount of air remains in the lungs, known as residual volume. So, the lungs doesn’t collapse even after forceful expiration.

Question. “If there were no algae there would be no fish in the sea”. Comment.
Answer. Algae produce 02 as a result of photosynthesis. l’his oxygen is utilized by the fishes in the sea for carrying out respiration. If there were no algae, no oxygen would have been produced. Thus, fishes might have died.

Question. Differentiate between single and double circulation found in vertebrates.

Question. What is the difference between arteries & veins?