Life Processes — Class 10 Science PYQs

Which of the following statement(s) is (are) true about human heart ?
(a) Right atrium receives oxygenated blood from lungs through pulmonary artery.
(b) Left atrium transfers oxygenated blood to left ventricle which sends it to various parts of the body.
(c) Right atrium receives deoxygenated blood through vena cava from upper and lower body.
(d) Left atrium transfers oxygenated blood to aorta which sends it to different parts of the body.

In human respiratory system, when a person breathes in, the position of ribs and diaphragm will be :

A stomata closes when :
(i) it needs carbon dioxide for photosynthesis.
(ii) it does not need carbon dioxide for photosynthesis.
(iii) water flows out of the guard cells.
(iv) water flows into the guard cells.

The correct reason(s) in this process is/are :

For Q. Nos. 17 to 20, two statements are given – One labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below :
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.

Assertion (A) : The rate of breathing in aquatic organisms is much faster than in terrestrial organisms.

Reason (R) : The amount of oxygen dissolved in water is very high as compared to the amount of oxygen in air.

(i) Give reason why herbivorous animals have longer, small intestine than carnivorous animals ?
(ii) Although 'Pepsin' and 'Trypsin' are both protein digesting enzymes yet they differ from each other. Justify this statement by giving one difference between them.

Two test tubes A and B are taken, each containing one mL of starch solution. Add $1\text{ mL}$ of saliva to test tube ‘A’ only and leave both the test tubes undisturbed for a few minutes. Now add a few drops of dilute iodine solution to both the test tubes.
(a) Which one of the two test tubes shows change in colour ? Write the changed colour observed in this test tube.
(b) What can we conclude from this activity ?

Photosynthesis takes place in the leaves and the food prepared by it reaches other parts of the plants. Name the process involved and explain it.

Mention the pathway of urine in our body starting from the organ of its formation to its excretion. What will happen if the tubular part of the nephron does not work properly?

(a) Give reasons for the following :
(i) Alveoli in lungs are richly supplied with blood capillaries.
(ii) Respiratory pigment in the blood takes up oxygen and not carbon dioxide.
(iii) During anaerobic respiration, a 3-carbon molecule is formed as an end product instead of ${\text{CO}}_2$ in human beings.

OR

(b) (i) Name the movements that occur all along the gut in human digestive system. How do they help in digestion ?
(ii) Where is bile juice stored in human body ? List two roles of bile juice.

In the context of the statement “chlorophyll is necessary for photosynthesis” answer the following questions :
(i) What are variegated leaves? Give an example.
(ii) When leaf is boiled in alcohol, what happens to the colour of the leaf and the colour of the solution ?
(iii) In what form is the carbohydrate produced, stored in the plant? Why is chlorophyll necessary for photosynthesis ?