CBSE Class 10 Science Life Processes VBQs

Question. Which of the following is not primarily required for activity of the protoplasm and maintenance of life in plants? 
(a) Water
(b) Suitable temperature
(c) Resin
(d) Food

Answer : C

Question. It is better to say that during inhalation in mammals 
(a) The diaphragm is lowered
(b) The diaphragm is lowered and external intercostal muscles contract
(c) Internal intercostal muscles contract and chest cavity is enlarged.
(d) The diaphragm is lowered and external intercostal muscles contract, thereby the ribs are raised upwards and out wards.

Answer : D

Question. By respiration we mean :- 
(a) exchange of gases through the stomata of a leaf
(b) taking in of oxygen and giving off of carbon dioxide through gills
(c) oxidation of food molecules and release of energy at cellular level
(d) exchange of gases through skin of an animal

Answer : C

Question. The raw materials for photosynthesis are :- 
(a) CO₂ and O₂
(b) Sunlight and CO₂
(c) Water and Chlorophyll
(d) CO2 and water

Answer : D

Question. Which of the following is the best equation representing photosynthesis ? 
(a) 6CO₂ + 6H₂O → chlorophyll C₆H₁₂O₆ 6O₂
(b) CO₂ + H2O → CH₂O + O₂
(c) 6CO₂ + 12H₂O + chlorophyll → sun light C6H₁₂O₆ + 6H₂O + 6O₂ ↑
(d) 12CO₂ + 6H₂O light → chlorophyll C6H12O6 + 6H2O + 6O2

Answer : C

Question. The requisite condition for dark reaction of photosynthesis is :- 
(a) absence of light
(b) presence of chlorophyll
(c) presence of carbon dioxide
(d) presence of O₂

Answer : C

Question. Suger (glucose) is produced as the first product of photosynthesis in a leaf. To test the sugar so formed, the suitable leaf would be :- 
(a) bean
(b) coleus
(c) croton
(d) onion

Answer : D

Question. Maximum amount of energy is released by the :- 
(a) conversion of glucose into lactic acid
(b) conversion of glucose into pyruvic acid
(c) oxidation of glucose to carbon dioxide and water
(d)conversion of sucrose to glucose

Answer : C

Question. Most plants use mainly the following portions of the visible spectrum for photosynthesis :- 
(a) red-organge
(b) yellow-orange
(c) blue-violet
(d) blue-violet and red-orange

Answer : D

Question. There are a number of inaccuracies in the above model for showing the breathing process except 
(a) the chest wall is not a rigid container, it ·has ribs which move upwards and downwards during breathing
(b) the diaphragm in the relaxed condition is dome shaped and during inspiration it becomes almost flat due to contraction of its muscles
(c) when the diaphragm (rubber sheet) is pulled downwards the volume in the chest cavity (bell jar) is increased
(d) the lungs are closely pressed to the chest wall and there is not so much space in the chest cavity as shown in the above model.

Answer : C

Question. When green leaves are crushed and dissolved in acetone, the different constituents of the extract which are separated by chromatography may be :- 
(a) chlorophyll a and chlorophyll b
(b) chlorophyll a, chlorophyll b and carotinoids
(c) chlorophyll a, chlorophyll b, carotinoids and anthocyans
(d) carotinoids and anthocyans

Answer : C

Question. The end product(s) of glycolysis is (are) :- 
(a) carbon dioxide and water
(b) amino acid
(c) pyruvic acid
(d) ethyl alcohol

Answer : C

Question. Since there is only 0.03% of CO₂ in the air and green plants use about 20% of the atmospheric CO2 each year, there is :- 
(a) danger of scarcity of CO₂ after 1000 years
(b) no danger of scarcity of CO₂
(c) a possibility of increase in the amount of CO₂ due to pollution in the air
(d) no danger of increase or decrease in amount of CO₂ in the air in times to come.

Answer : C

Question. Stomata and lenticles may also be considered as excretory structures because :- 
(a) they allow carbon dioxide from the air to enter into a leaf
(b) carbon dioxide and water vapour produced during respiration and not used during photosynthesis diffuse into the air spaces and pass out through the stomata and lenticels
(c) they allow water vapour from the surrounding air to enter into a leaf
(d) they allow nutrients to enter into a leaf

Answer : B

Question. Organic acids which may be poisonous to a plant are stored in :- 
(a) vacuoles
(b) mesophyll tissue
(c) palisade cells
(d) xylem vessels

Answer : A

Question. To increase the nitrogen content of soil, which of the following would you suggest as an economic method, that would also improve soil structure ? 
(a) Adding chemical fertilisers
(b) Removing the upper crust which may be poor in nitrogen
(c) Growing leguminous plants/green manuring
(d) Irrigation to increase bacterial activity

Answer : C

Question. Water absorbed by root hairs of a plant can rise to the highest point by means of :- 
(a) root pressure
(b) force of capillarity
(c) transpiration pull
(d) diffusion

Answer : C

Question. In an insect the oxygen reaches the tissues through 
(a) Blood
(b) Spiracles
(c) Tracheae
(d) Stomata

Answer : C

Question. Most of the photosynthesis (80%) which takes place on this earth is carried on by :- 
(a) green plants on land
(b) algae present in fresh water
(c) algae found in ocean
(d) algae present in ocean and fresh water sources

Answer : D

Question. The source of oxygen which is given out during the process of photosynthesis is :- 
(a) water
(b) carbon dioxide
(c) the air surrounding the chloroplasts
(d) the air surrounding the leaf

Answer : A

Question. When chemical fertilisers are supplied to a plant without supplying sufficient water, the plant shows wilting because :- 
(a) the plant cannot absorb the fertilisers
(b) the plant absorbs more fertilisers
(c) of plasmolysis occurring in root cells
(d) the fertiliser absorbs all available water in the soil

Answer : C

Question. Transpiration is an essential process in plants as it :- 
(a) helps concentrate the cell-sap and thereby helps osmosis
(b) creates a suction force called transpitration-pull which is a great force in the ascent of sap
(c) cools down the temperature in and around the plant
(d) is responsible for all the three processes mentioned above and some others 

Answer : D

Question. Girdling experiment and presence of tagged sufar with 14C in the phloem tissue of a stem proves that the prepared food materials are transported through :- 
(a) xylem
(b) phloem
(c) cortex
(d) pericycle

Answer : B

Question. Cuscuta is a :- 
(a) total parasite
(b) semiparasite
(c) saprophytic
(d) holozoic

Answer : A

Question. Most of the carbon dioxide is carried by the blood from cells to the lungs 
(a) in dissolved condition in the plasma
(b) in the form of bicarbonate ions
(c) in the form of oxyhaemoglobin
(d) in gaseous form.

Answer : B

Question. Plants suffering from chlorosis are abnormally pale and cannot carry out photosynthesis properly. To prevent chlorosis, plants require :- 
(a) nitrogen
(b) iron
(c) magnesium
(d) nitrogen and magnesium

Answer : D

Question. Respiration in yeast :- 
(a) takes place in the presence of oxygen
(b) yields lactic acid and carbon dioxide
(c) is anaerobic and produces carbon dioxide
(d) takes place only in darkness

Answer : C

Question. Metabolic water is considered as a waste product because :- 
(a) water is formed from the union of hydrogen and oxygen
(b) it is produced during metabolic activity of a plant or animal
(c) the water which is produced in excess, is given out of the body
(d) of the reasons given in (a) and (c)

Answer : D

Question. The first product of photosynthesis which can be tested in a laboratory is :- 
(a) PGAL
(b) pyruvic acid
(c) glucose
(d) starch

Answer : C

Question. In oxidation of carbohydrates, most of the energy is released during the change from :- 
(a) starch to maltose
(b) maltose to glucose
(c) glucose to pyruvic acid
(d) pyruvic acid to CO₂ and H₂O

Answer : D

Question. Which chemical reaction takes place during dark reaction of photosynthesis ? 
(a) Photolysis
(b) Hydrolysis
(c) Carbon dioxide is bonded with hydrogen
(d) Nitrogen fixation

Answer : C

Question. When there is an increase of carbon dioxide in the blood 
(a) heart beat is increased
(b) heart beat is decreased
(c) breathing rate and heart beat are increased
(d) breathing rate is' decreased and heart rate is increased.

Answer : C

Question. The colour of light which is absorbed most by a chlorophyll solution is :- 
(a) blue
(b) green
(c) orange
(d) red

Answer : D

Question. Exchange of gases takes place in a leaf in :- 
(a) the palisade tissue
(b) spongy parenchyma
(c) vascular tissue
(d) upper epidermis

Answer : B

Question. For finding out the source of oxygen liberated during photosynthesis by a green plant, the scientists used :- 
(a) radioactive isotope of oxygen
(b) stable isotope of oxygen O¹⁸
(c) radioactive carbon (¹⁴C)
(d) heavy water

Answer : B

Question. The nutrition in a mucor is :- 
(a) parasitic
(b) autophytic
(c) saprophytic
(d) holozoic

Answer : C

Question. Which of the following is not an excretory product in a plant ? 
(a) Glucose produced during photosynthesis
(b) Turpentine oil
(c) Latex
(d) Oxygen

Answer : A

Question. Do you agree with the statement that plants take in carbon dioxide and give out oxygen during respiration ? 
(a) Yes, we see that during the day green plants take in carbon dioxide and give out oxygen
(b) Yes, people grow plants in and around their houses
(c) No, plants take in oxygen and carbondioxide throughout day and night during respiration
(d) Plants take in carbon dioxide during the day and give out oxygen. Plants take in oxygen and give out carbon dioxide at night

Answer : C

Question. During respiration much of the chemical energy of organic molecules is transferred to become part of :- 
(a) ATP
(b) ADP
(c) carbon dioxide
(d) oxygen

Answer : A

Question. For the production of cellular energy it is essential to have :- 
(a) free molecular oxygen
(b) bounded oxygen
(c) free CO₂
(d) air

Answer : D

Question. Which of the following reactions takes palce during anaerobic respiration ? 
(a) 6CO₂ + 12H₂O → C6H₁₂O₆ + 6H₂O + 6O₂ + ATP
(b) C₆H₁₂O₆ + 6O₂ →6O₂ + 6H₂O + 38 ATP
(c) C₆H₁₂O₆ → 2CO₂ + 2C₂H₅OH + 2 ATP
(d) C₆H₁₂O₆ → 2CO₂ + 2C₂H₅OH + 30 ATP

Answer : C

Question. In land plants exchange of gases takes place throught :- 
(a) stomata and lenticels
(b) stomata only
(c) lenticels only
(d) general surface of a leaf

Answer : A

Question. Two types of plant tissues specialised for transport are :- 
(a) cambium and meristematic cells
(b) sclerenchyma and collenchyma
(c) xylem and phloem
(d) pith and cortex

Answer : C

Question. Which one is the compreshensive answer regarding waste products produced by a plant ? 
(a) CO₂ is produced during respiration
(b) CO₂ is produced during respiration and oxygen is produced during photosynthesis
(c) CO₂, O₂ are produced as waste products and food is stored in storage organs
(d) CO₂, O₂ and water vapour are produced during various cellular processes

Answer : D

Question. The function(s) of root hairs is (are) :- 
(a) to absorb water
(b) to fix the plant in the soil
(c) to absorb water and mineral ions
(d) to provide large surface area for absorption

Answer : C

Question. The absorption and transport of minerals by the root hairs, and from cell to cell is carried out by :- 
(a) passive transport
(b) active transport
(c) osmosis
(d) diffusion

Answer : B

Question. The plant's ability to raise water through the stem upto the leaves is least affected by the :- 
(a) leaf surface area
(b) thickness of the bark of the tree
(c) number of root hairs
(d) diameter of xylem vessels

Answer : B

Question. Which of the following is not characteristic of a good respiratory surface ? 
(a) Thin and moist
(b) Large surface area
(c) Close to oxygen and gas transport
(d) Thick and dry surface

Answer : D

Question. The transportation of water from the roots to the leaves via the stem is called :- 
(a) transpiration pull
(b) transpiration stream
(c) translocation
(d) root pressure

Answer : B

Question. Which part of the cell is most directly concerned with the exchange of materials between the cell and its environment :- 
(a) Nuclear membrane
(b) Cell wall
(c) Ribosomes
(d) Cell membrane

Answer : D

Question. Respiratory gases enter and leave a plant through all the following except :- 
(a) vascular bundles
(b) stomata
(c) general surface of the roots
(d) lenticles in a stem

Answer : A

Question. Preparation bread depends on the actiity of organisms which obtain energy through :- 
(a) fermentation
(b) aerobic respiration
(c) photosynthesis
(d) biosynthesis

Answer : A

Question. When one does vigorous exercise, he breathes heavily and the muscles fatigue. This is due to the formation of lactic acid in the muscles. Then he stops exercise and 
(a) lactic acid is brought to the liver and converted into glucose
(b) lactic acid is converted into CO₂ and water with the aid of more oxygen.
(c) lactic acid is brought by the blood to the liver and there it is converted into glycogen.
(d) Any one of the above processes may take place.

Answer : D

Question. Plants do not have organised excretory system because :- 
(a) there is not much activity in plants
(b) excess of nitrogen is rarely left over from the breakdown processes and they do not need strict control of ionic concentration of their cells for cellular activities
(c) nitrogenous compounds are not present in the plant
(d) all the cells arein direct communication with the environment.

Answer : B

Question. Girdling a tree by cutting a band through the bark completely around the trunk cuts all the phloem tubes. As a result :- 
(a) leaves above the girdle die
(b) all the leaves die
(c) leaves below the girdle die
(d) roots die and when food is exhausted the whole tree dies

Answer : D

Question. The presence of sugar in onion leaves can be tested with :- 
(a) iodine solution
(b) copper sulphate solution
(c) lime water
(d) Benedict solution

Answer : D

Question. Most of the photosynthesis is carried on in palisade cells because :- 
(a) of their orientation with the upper surface and arrangement of chloroplasts in them
(b) they get maximum sunlight
(c) they have maximum number of chloroplasts
(d) of all the above reasons

Answer : D

Question. For studying the rate of transpiration we use :- 
(a) atmometer
(b) cobalt chloride paper
(c) potometer
(d) porometer

Answer : C

Question. The correct order of steps occurring in animals is:
(a) Ingestion, Absorption, Digestion, Assimilation, Egestion
(b) Ingestion, Digestion, Assimilation, Absorption, Egestion
(c) Ingestion, Digestion, Absorption, Assimilation, Egestion
(d) Ingestion, Assimilation, Digestion, Absorption, Egestion

Answer : C

Question. Which option correctly shows the transport of oxygen to the cell?
(a) Lungs →pulmonary vein →left atrium →left ventricle →aorta → body cells
(b) Lungs →pulmonary vein →right atrium →right ventricle → aorta → body cells
(c) Lungs →pulmonary artery →left atrium → left ventricle → vena cava → body cells
(d) Lungs →pulmonary artery →right atrium → right ventricle→ vena cava → body cells

Answer : A

Question. In which of the following groups of organisms, food materials are broken down outside the body and absorbed?
(a) Mushroom, green plants, Amoeba
(b) Yeast, mushroom, bread mould
(c) Paramecium, Amoeba, Cuscuta
(d) Cuscuta, lice, tapeworm

Answer : B

Question. A plant gets rid of excess water through transpiration. Which is a method used by plants to get rid of solid waste products?
(a) shortening of stem
(b) dropping down of fruits
(c) shedding of yellow leaves
(d) expansion of roots into the soil

Answer : C

Question. Glycolysis process occurs in which part of the cell?
(a) Cytoplasm
(b) Nucleus
(c) Mitochondria
(d) Chloroplast

Answer : A

Question. How is food transported from phloem to the tissues according to plants’ needs?
(a) food is transported along with the water in the plant’s body.
(b) food is transported in only one direction like water in the plant body through xylem.
(c) food is transported from a region with low concentration to higher concentration.
(d) food is transported from a region where it is produced to other parts of the plants.

Answer : D

Question. Single circulation, i.e., blood flows through the heart only once during one cycle of passage through the body, is exhibited by which of the following:
(a) hyla, rana, draco
(b) whale, dolphin, turtle
(c) labeo, chameleon, salamander
(d) hippocampus, exocoetus, anabas

Answer : D

Question. In which mode of nutrition an organism derives its food from the body of another living organism without killing it?
(a) Saprotrophic nutrition
(b) Parasitic nutrition
(c) Holozoic nutrition
(d) Autotrophic nutrition

Answer : B

Question. Which of the following events in the mouth cavity will be affected if salivary amylase is lacking in the saliva?
(a) Starch breaking down into sugars.
(b) Proteins breaking down into amino acids.
(c) Absorption of vitamins.
(d) Fats breaking down into fatty acids and glycerol.

Answer : A

Very Short Answer Type Question

Question. What will happen to a plant if its xylem is removed?
Answer : Xylem in plant transports water and dissolved mineral nutrients from the roots to all 
parts of the vascular plant. So, if xylem is removed from the plant, the water and mineral supply to the plant will stop and therefore, the plant will die.

Question. What would be the consequences of deficiency of hemoglobin in your body?
Answer : The deficiency of hemoglobin in our body is called anemia. In anemia, the blood is unable to carry the sufficient amount of oxygen required by the body. So, respiration would be less and less energy will be available to the body. The hemoglobin deficient person will feel weak, pale, lethargic and will be unable to perform heavy physical work.

Question. Name the process in plants where water is lost as water vapour. :
Answer : Transpiration is the process when plants loose water as vapour.

Question. Name two excretory products other than 0₂ and CO₂ in plants.
Answer : The two excretory products other than 0₂ and CO₂ in plants are resins and gums.

Question. State the basic difference between the process of respiration and photosynthesis.
Answer : Respiration uses O₂ and releases CO₂ but in photosynthesis, CO₂ is used and O₂ is released.

Question. How would it affect the digestion of proteins and carbohydrates in the duodenum of man if there is a blockage in the pancreatic duct? Explain.
Answer : If there is a blockage in the pancreatic duct, the pancreatic juice which contains enzymes for the digestion of carbohydrates and proteins will not reach the small intestine.

Question. Name the intermediate and the end products of glucose breakdown in aerobic respiration.
Answer :

Question. Mention how organisms like bread moulds and mushrooms obtain their food.
Answer : Organisms like bread moulds and mushrooms breakdown the food materials outside the body and then absorb the nutrients of the bread.

Question. Name the green dot like structures in some cells observed by a student when a leaf peel was viewed under a microscope. What is this green colour due to?
Answer : The green dot-like structures in some cells observed by a student when a leaf peel is viewed under a microscope are chloroplasts. The green colour is due to the presence of green pigment, chlorophyll.

Question. Mention two structural features of small intestine which add to the absorptive capacity.
Answer : Two structural features of small intestine are:
(i) Villi is present to increase the absorptive surface area.
(ii) Lacteals in the villi receive the products of fat digestion.

Question. What are the final products after digestion of carbohydrates and proteins?
Answer : The final product produced after digestion of carbohydrates is glucose and of proteins is amino acids.

Question. In the experiment “Light is essential for photosynthesis”, why does the uncovered part of the leaf turn blue-black after putting iodine solution?
Answer : Starch is produced in the uncovered part of the leaf because it is exposed to sunlight allowing it to photosynthesize, which turns blue-black in presence of iodine solution.

Question. Mention the raw materials required for photosynthesis.
Answer :The following raw materials are required for photosynthesis:
(i) Carbon Dioxide: Plants get CO2 from atmosphere through stomata.
(ii) Water: Plants absorb water from soil through roots and transport to leaves.
(iii) Sunlight: Sunlight, which is absorbed by the chlorophyll and other green parts of the plant.

Question. Why are white blood corpuscles called ‘soldiers’ of the body?
Answer : White blood corpuscles can fight with the disease germs present in the body carried by blood and help to maintain a healthy body. So, they are called as ‘soldiers’ of the body.

Question. What is the mode of nutrition in human beings?
Answer : Holozoic nutrition.

Short Answer Type Questions

Question. What is saliva? State its role in the digestion of food.
Answer : Saliva is a watery fluid secreted by the salivary glands in the mouth. The digestive

functions of saliva include moistening food, and helping to create a food bolus, so it can be swallowed easily. Saliva contains the enzyme amylase that breaks some starches down into maltose and dextrin.

Question. Explain the process of nutrition in Amoeba.
Answer : The mode of nutrition in Amoeba is holozoic. It feeds on unicellular plant or animal.
The various steps of nutrition are ingestion, digestion, assimilation and egestion. When Amoeba comes in contact with food particles, it sends out pseudopodia, which engulfs the prey by forming a food cup, which is known as ingestion. When the tips of the encircling pseudopodia touch each other, the food is encaptured into a bag called food vacuole. The food vacuole serves as a temporary stomach secreting digestive juice, this step is known as digestion. The digested food gets absorbed and diffuses into the cytoplasm and then assimilated. Egestion of undigested food takes place at any point on the surface of the body.

Question. Name the acid presents in the following:
(i) Tomato (ii) Vinegar (iii) Tamarind
Answer : (i) Oxalic acid (ii) citric acid (iii) Tartaric acid.

Question. How are the alveoli designed to maximise the exchange of gases?
Answer : Alveoli are small pouches or sacs like structure. They are surrounded by blood capillaries. Thus a large amount of air is brought in contact with the air in the lungs. More than millions of alveoli are present in the lungs. The presence of millions of alveoli in the lungs provides a very large surface area for the exchange of gases. The availability of large surface area maximises the exchange of gases.

Question. Why are the walls of ventricles thicker than the auricles ?
Answer : The walls of ventricles are thicker than the auricles because ventricles have to pump the blood to all the parts of the body during their contraction. To counteract the backward pressure exerted by the blood, the walls of the ventricles have to be thicker otherwise it may lead to bursting of heart.

Question. Explain the mechanism of gaseous exchange between tissues and blood.
Answer : Exchange of respiratory gases, i.e. oxygen and carbon dioxide occurs between the blood and tissues.
In tissues, oxygen is used up for their activities and carbon dioxide is released. The blood from lungs has high concentration of oxygen and low concentration of carbon dioxide. Due to this, difference in concentration of oxygen and carbon dioxide, the exchange of gases takes place between tissue and blood.

Question. What are enzymes? Name any one enzyme of our digestive system and write its function.
Answer : Enzymes are biological catalysts. Catalysts are proteins that increase the rate of chemical reactions without being used up. For example: Amylase catalyses the breakdown of starch into sugars in the mouth and small intestine

Question. (i) Write the balanced chemical equation for the process of photosynthesis,
(ii) When do the desert plants take up carbon dioxide and perform photosynthesis ?
Answer : (i) Photosynthesis can be represented using a chemical equation. The overall balanced equation is

(ii) Desert plants open up their stomata during night and take in CO₂. Stomata remains close during the day time to prevent the loss of water by i transpiration. They store the CO2 in their cells until the sun comes out and they can carry on with photosynthesis during the day time.

Question. Why there is no mixing of deoxygenated and oxygenated blood in the human heart normally?
Answer : There is no mixing of deoxygenated and oxygenated bloods in human heart due to the presence of inter-ventricular septum. This septa completely divides the ventricle into right and left to avoid mixing of blood.

Question. In single celled organisms diffusion is sufficient to meet all their requirements of food, exchange of gases or removal of wastes but it is not in case of multicellular organisms.
Explain the reason for this difference.
Answer : Unicellular organisms can absorb sufficient oxygen because of its complete contact with the atmosphere, but in multicellular organisms the rate of absorption and diffusion becomes very less because all cells are not in direct contact with the atmosphere. Multicellular organisms require greater amount of oxygen to sustain life processes which cannot be fulfilled by the process of diffusion.

Question. Why do herbivores have longer, small intestine than carnivores ?
Answer : Digestion of cellulose takes a longer time. Hence, herbivores eating grass need a longer small intestine to allow complete digestion of cellulose. Carnivorous animals cannot digest cellulose due to the absence of enzyme CELLULASE, hence they have a shorter intestine.

Question. State the role of the following in human digestive system :
(i) Digestive enzymes (ii) Hydrochloric acid (iii) Villi
Answer : (i) Digestive enzymes – Foods need to be broken into their small or simpler
molecules so that they can be absorbed into the bloodstream. However, the physical breakdown of food is not enough. Enzymes are hence needed for the chemical breakdown of food and speeding up the digestive process. The products of digestion can hence be small enough to be absorbed.
(ii) Hydrochloric acid – Hydro chloric acid helps to kill the germs which might have entered in to the system through food. It creates acidic medium for the pepsin to act on food to breakdown proteins.
(iii) Villi – Villi are finger like projections in the small intestine. They help to increase the surface area for absorption of the digested food. Villi are richly supplied with blood vessel which help to absorb digested food in to the blood stream.