Very Short Answer Questions - 1 Mark
Que 1. Why is energy required by an organism even during sleep?
Ans. This is because even when an organism is asleep, various biological processes keep on occurring in its body which requires energy.
Que 2. Give the energy transformation that takes place in the process of photosynthesis.
Ans. Solar energy is converted into chemical energy during photosynthesis.
Que 3. What is chlorophyll?
Ans. Chlorophyll is a green coloured pigment found in the green leaves or green parts of the plant which traps solar energy for photosynthesis. Chlorophyll is present in cell organelles called chloroplasts.
Que 4. Name the various factors which affect the rate of photosynthesis.
Ans. The factors which affect the rate of photosynthesis are light, water, temperature and carbon dioxide.
Que 5. Define photolysis.
Ans. The phenomenon of breaking down of water molecule using solar energy absorbed by chlorophyll molecules is known as photolysis.
Que 6. Define light reaction.
Ans. A chemical reaction, which take place only in the presence of light, is called light reaction or light dependent reaction. It takes place in grana of chloroplast.
Que 7. Define dark reaction.
Ans. A chemical reaction, which can take place even in the absence of light, is called a dark reaction or light independent reaction. It takes place in stroma of chloroplast.
Que 8. What are peristaltic movements?
Ans. The contraction and expansion movements of the walls of foodpipe are called peristaltic movements. This movement pushes the food in forward direction in the alimentary canal.
Que 9. Which is the largest gland in the human body?
Ans. Liver
Que 10. Give an example of an organism whose digestion is intracellular.
Ans. Amoeba
Que 11. Name the various cells through which water moves upward to reach the leaves.
Ans. water absorbed by root hairs moves through epidermis → root cortex → endodermis → root xylem (ie., tracheids and vessels) → stem xylem → xylem in the leaf.
Que 12. What will happen to a plant if its xylem is removed?
Ans. The xylem tissue transports water and minerals from the soil to the leaves of a plant for photosynthesis. If xylem is removed, upward movement of water will stop leading to wilting of leaves and ultimately causes death of a plant.
Que 13. In which chamber of heart is oxygenated and deoxygenated blood found?
Ans. Oxygenated blood: It is found in left auricle and left ventricle.
Deoxygenated blood: It is found in right auricle and right ventricle.
Que 14. What makes red blood corpuscles red?
Ans. Haemoglobin
Que 15. What is the main function of kidneys in humans?
Ans. Kidneys excrete water and dissolve metabolic wastes, e.g., urea and other dissolved solids like uric acid, creatinine and inorganic salts.
Que 16. In which part of nephron is water reabsorbed?
Ans. Proximal and distal convoluted tubules.
Que 17. In which region of kidney Malpighian corpuscles are found?
Ans. In the outer (cortex) part of kidney.
Que 18. What process in plants is known as transpiration?
Ans. The release of water vapours in the atmosphere through the pores present on plant leaves, i.e., stomata, is called transpiration.
Que 19. What is urethra?
Ans. The urine collected into the urinary bladder passes through a muscular tube which is called urethra.
Que 20. Which is the major nitrogenous waste product in human beings? How is it removed from the body?
Ans. The major nitrogenous waste product in human beings is urea. Urea is removed/ eliminated from the body through urine.
Que 21. Name the membrane covering the lungs.
Ans. Pleura
Que 22. What is osmoregulation?
Ans. Osmoregulation is the maintenance of optimum concentration of water and salts in the body fluids.
Que 23 In which form
(i) oxygen is carried to the tissues?
(i) CO2 moves out of the blood?
Ans. (i) Oxyhaemoglobin
(ii) Carboxyhaemoglobin and as carbonic acid (CO2 dissolved in blood plasma).
Que 24. Why do the walls of trachea not collapse when there is less air in it?
Ans. Tracheal walls do not collapse when there is less air in it because it is supported by rings of cartilage.
Que 25. Which part of root is involved in the exchange of respiratory gases in plants?
Ans. Root hairs are involved in the exchange of respiratory gases in plants.
Que 26. Name two organisms in which food material is broken down outside the body and absorbed.
Ans. Yeast, mushroom.
Que 27. What prevents backflow of blood inside the heart during contraction?
Ans. Valves in heart prevent backflow of blood inside the heart during contraction.
Que 28. Which is the first enzyme to mix with food in the digestive system?
Ans. Salivary amylase
Que 29. Why does lack of oxygen in muscles often lead to cramps among cricketers?
Ans. This is due to the conversion of pyruvate to lactic acid in the absence of oxygen.
Que 30. Where is pyruvic acid converted into lactic acid during deficiency of oxygen in tissues of human beings?
Ans. Golgi body
Que 31. Where does the oxygen come from when it is liberated during photosynthesis?
Ans. Oxygen liberated during photosynthesis comes from water.
Que 32. What is the internal (cellular) energy reserve in autotrophs?
Ans. Starch
Que 33. In which forms do most plants absorb nitrogen?
Ans. Nitrates and nitrites
Que 34. If salivary amylase is lacking in the saliva, which event in the mouth cavity will be affected?
Ans. Starch breaking down into sugars.
Que 35. What protects the inner lining of stomach from hydrochloric acid?
Ans. The inner lining of stomach is protected from hydrochloric acid by mucus.
Que 36. What is chyme?
Ans. The slightly digested food, enters into the stomach through the alimentary canal. In the stomach, this food is churned along with gastric juices converting this food into a semi-solid paste called chyme.
Que 37. Name the enzyme which is present in infants but may be absent in adults.
Ans. Renin