Life Processes — Class 10 Science PYQs

(A) / Both, Assertion (A) and Reason (R) are true and Reason (R) is
the correct explanation of the Assertion (A).
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(A)/ Both A and R are true, and R is the correct explanation of A. (1 Mark)

(B) / Ozone shields earth's surface from harmful infra - red radiations. (1)

(B) / Stomata (1 Mark)

(A) / Starch (1 Mark)

(B) / (ii) and (iii)

(D) / $\ce{6CO2 + 12H2O ->[Chlorophyll][Sunlight] C6H12O6 + 6O2 + 6H2O}$ (1 Mark)

• Food:
▪ P – Glucose (½ Mark)
▪ Q – Starch (½ Mark)
• Raw materials: $\ce{CO2}$, $\ce{H2O}$ (½ Mark)
• Conditions: Presence of sunlight, chlorophyll (½ Mark)

(B) / Trypsin digests proteins and lipase digests emulsified fats (1 Mark)

(A)/ Both A and R are true and R is the correct explanation of A. (1 Mark)

• Liver/Pancreas/Small intestine. (1 Mark)
• Bile salts break down big globules of fat into small globules so that an enzyme can act on it / emulsification of fats. (1 Mark)
Lipase enzyme digests emulsified fats into simple form.
• Intestinal juice enzymes finally concert it into fatty acid and glycerol.
In Small intestine. (1 Mark)

(D)/Glucose $\rightarrow$ pyruvate $\xrightarrow{\text{lack of oxygen}}$ Lactic acid + Energy (1 Mark)

u2022 Aerobic Respiration
u2022 Complete breakdown of glucose takes place in presence of oxygen releasing more energy.

A: Cytoplasm
B: Ethanol
C: Carbon dioxide
D: Lactic acid
E: Carbon dioxide
F: Water

• The main function of the diaphragm is to flatten during inhalation,
which expands the chest cavity and draws the air into the lungs
/ helps in breathing. (1)
• It is located at the base of chest cavity. (1)

The lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for the carbon dioxide to be released. (2)

(A) / Both Assertion (A) and Reason (R) are true and (R) is the correct explanation of (A). OR (C)/ Assertion (A) is true but Reason (R) is false. (1 Mark)

(D) / Contraction of Left Ventricle. (1 Mark)

(D) / Mammals (1 Mark)

(D) / Aorta takes oxygenated blood from heart to body parts. (1 Mark)

I. (i) 2-chambered
(ii) Amphibians/Reptiles
(iii) Double circulation
II. Double circulation

• Oxygenated blood from lungs comes to left atrium which pushes it to left ventricle $\rightarrow$ (½ Mark)
• Left ventricle contracts to push blood into aorta, to be sent to body parts $\rightarrow$ (½ Mark)
• Deoxygenated blood from body parts is collected and sent to right atrium $\rightarrow$ (½ Mark)
• Right atrium pushes it to right ventricle, to be sent to lungs for oxygenation. (½ Mark)

(a) Some waste is stored in leaves that fall off/wastes may be stored in cellular vacuoles/other wastes are stored as resins and gums in old xylem/ may excrete some waste into soil via roots. (1 Mark)
(b) Mammals and birds have high energy needs to maintain their body temperature. Therefore, mixing of blood is prevented by separation of right and left side of heart and thus they have double circulation. (2 Marks)

(D) / The guard cells have swelled due to inflow of water

(A) / Entry of water into guard cells. (1 Mark)

(D) / Organic substance from leaves to the other parts of the plant. (1 Mark)

(C)/ Guard cells (1 Mark)

• Necessary- It helps in transport of water and minerals from roots to leaves / It helps in temperature regulation. (1 Mark)
• Evil - It results in loss of water. (1 Mark)

u2022 Root pressure: Cells in the contact of the soil actively take up ions and creates a difference in concentration between roots and soil, water moves from soil to root to eliminate this difference.
u2022 Transpirational pull: Water lost through transpiration from aerial parts of plants, creates a suction which pulls water column from xylem cells of roots.

(B)/ Both A and R are true but R is not the correct explanation of A

(C) / A cluster of thin-walled capillaries richly supplied with blood. (1 Mark)

(a)
• Bile emulsifies fats for their digestion.
$\frac{1}{2}$
• It makes medium alkaline for further digestion by pancreatic
and small intestinal enzymes.
$\frac{1}{2}$
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(b) Glucose, water, salt, amino acid
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(a) • Structure $\rightarrow$ Bowman’s capsule is a cup shaped end of a coiled tube (nephron) (½ Mark)
• Function $\rightarrow$ Bowman’s capsule collects the filtrate from the blood. (½ Mark)
(b) Most of the water, salt, glucose, amino acids are selectively reabsorbed from the filtrate into the blood as the urine flows along the tubular part of nephron. (1 Mark)
(c) • Excretion is the process of removal of metabolic wastes/ nitrogenous waste/ urea/uric acid from the body. (1 Mark)
• It is essential for survival of a living organism as the excretory products are toxic and harmful to the organism. (1 Mark)
OR
(c) • Both lungs and kidneys remove metabolic waste / Lungs remove carbon dioxide gas ($\ce{CO2}$) from the blood while kidneys remove nitrogenous wastes like urea from the blood. (1 Mark)
• Both lungs and kidneys have thin-walled blood capillaries involved in exchange of gases and filtration of blood respectively. (1 Mark)

(D) / Flowers can store some waste products
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