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Q 1. How are water and
minerals absorbed by the plant?
Solution
In the roots, cells in
contact with the soil actively take up the ions. It creates a difference in the
concentration of these ions between roots of soil. To eliminate this
difference, water moves into the roots from the soil. Thus, water and minerals
are absorbed by the plants.
Q 2. You have visited a zoo
where you have observed that a fish is respiring with a faster rate whereas the
crocodile is not. Explain the reason behind it.
Solution
Aquatic animals like fish
absorb O2 in dissolved form and since the amount of dissolved O2 is
fairly low compared to amount of O2 in the air, the rate of
breathing in aquatic organism is faster than that of crocodile.
Q 3. What happens to
glucose that enters the nephron along with the filtrate?
Solution
Glucose that enters the
nephron along with the filtrate after passing through the glomerulus, passes
from the tubule of nephron where it is selectively reabsorbed and sent back to
blood.
Q 4. What is site for the
breakdown of pyruvate to release carbon dioxide, water and energy in our
bodies?
Solution
Breakdown of pyruvate
takes place in mitochondria and results in the release of carbon dioxide,
water and energy
Q 5. How an artery is
different from the vein?
Solution
Artery Vein i. Carry
oxygenated blood. ii. Walls are thick. iii. Carry blood from heart to various
body parts. i. Carry deoxygenated blood. ii. Walls are thin. iii. Carry
blood from various body parts to heart.
Q 6. In the Lungs: What
substance is taken into the body? What substance is removed from the
body?
Solution
O2 CO2
Q 7. How are the alveoli
designed to maximize the exchange of gases ?
Solution
Large numbers of alveoli
in the lungs provides a very large surface area for the exchange of gases.
Walls of alveoli contain an extensive network of blood vessels. Walls of
alveoli are extremely thin and made of single layer of cells. (any two)
Q 8. A scientist while
performing an experiment, first places an RBC in an concentrated salt solution
and then in distilled water. Write the observation in both the cases.
Solution
In the first case, when
RBC is placed in the concentrated salt solution it will shrink due to loss of
plasma (water) into the surrounding solution. While in distilled water, it will
regain its shape by becoming turgid due to absorption of water.
Q 9. How opening and
closing of stomata is regulated in the leaves of plants?
Solution
The opening and closing
of stomata is controlled by the guard cells. When water flows into the guard
cells, they swell up and the curved surface causes the stomata to open. When
the guard cells loses water, they shrink and become flacid and straight thus
closing the stomata.
Q 10. What happens when two
non matching blood groups are mixed?
Solution
When two different types
of bloods are mixed together, it causes blood clumping or agglutination of
blood. When two different blood groups are combined the antigen present in one
group binds with the antibodies of other blood group and results in
agglutination of blood which leads to rupture of erythrocytes which may be
fatal for the patient.
Q 11. What will happen if
the blood is deficient in haemoglobin?
Solution
If the blood is deficient
in the haemoglobin then less amount of O2 reaches to tissues
due to which less energy will be released as less O2 bind with
the haemoglobin.
Q 12. A kind of blood cell
engulf the foreign particles that enter in our body. Name it and why it do so?
Solution
Leucocytes produces
antibodies which kill the harmful germs that enter our body.
Q 13. Name the products
formed after complete digestion of carbohydrates, proteins and fats in small
intestine.
Solution
In small intestines, the
intestinal juice contains a number of enzymes which complete the digestion
process by converting complex carbohydrates into glucose, proteins into amino
acids and fats into fatty acids and glycerol.
Q 14. How does HCl in the
human stomach help in digestion of food?
Solution
1. HCl helps in
activating pepsin, a protein-digesting enzyme. 2. It kills any germs which may
have entered the body along with food.
Q 15. (i) Why are valves
needed in the heart? (ii) Leakage of blood from vessels reduces the efficiency
of pumping system. How is the leakage prevented?
Solution
(i) Valves ensure that
blood does not flow backward when the atria or ventricles contract. (ii) To
avoid leakage blood has platelet cells which circulate around the body and plug
the leakage by clotting the blood at the point of injury.
Q 16. What is contraction
and relaxation of the wall of the digestive tract called?
Solution
The contraction and relaxation
of the wall of the digestive tract is called peristalsis.
Q 17. How water and
minerals are transported in the plants?
Solution
Water and minerals
in plants are absorbed from soil by the roots of the plants and transported to
various parts of the plants through xylem vessels due to root pressure and
transpiration.
Q 18. What is cardiac
cycle? Name its various events.
Solution
Cardiac cycle is the
sequence of events which occur from beginning of one heartbeat to the beginning
of next. Various phases are:- atrial systole, ventricular systole and
complete diastole
Q 19. Explain the digestion
in stomach.
Solution
The gastric glands in the
stomach secrete: (i) HCl - It kills the bacteria ingested with food and makes
the medium of food acidic so as to facilitate the action of the enzyme pepsin.
(ii) Pepsin - It helps to digest proteins. (iii) Mucus - It protects the inner
lining of the stomach from the action of HCl.
Q 20. Which organelle is
associated with production of energy by aerobic respiration?
Solution
Mitochondria are
associated with production of energy by aerobic respiration.
Q 21. A cup shaped
structure in the nephron receives blood through a network of capillaries. What
is this network of capillaries known as and what is its main function?
Solution
The bundle of capillaries
constitutes the glomerulus. It helps in the filtration of blood.
Q 22. Most of the CO2 produced
in a tissue enters the red blood cells by diffusion. What happens to this CO2?
Solution
Most of the CO2 produced
in a tissue enters the RBC's of blood by diffusion. RBC’s consist of a pigment
known as haemoglobin which binds with CO2 and get transported
to the lungs through blood from where it is released out through nostrils.
Q 23. Nephron is
responsible for the formation of urine. Explain the structure of nephron.
Solution
Nephron is the structural
unit of kidney which consists of a long tubule. One end of the tubule is
connected to Bowman's capsule, a cup shaped structure, followed by a tubular
part consisting of proximal convoluted tubule, loop of Henle and distal
convoluted tubule. Bowman's capsule contains a bundle of blood capillaries
called glomerulus which filter the blood. The function of tubular part on the
other hand is selective reabsorption of useful substances.
Q 24. Leaves of a healthy
potted plant were coated with vaseline. Will this plant remain healthy for
long? Give reasons.
Solution
The plant will not remain
healthy for a long time because: i. It would not get oxygen for respiration.
ii. It would not get carbon dioxide to carry out photosynthesis. iii. The
upward movement of water and minerals would be hampered due to lack of
transpiration.
Q 25. What happens to the
plant cell when we keep it in the hypotonic solution?
Solution
When we keep plant
cell in the hypotonic solution it absorbs water from the surroundings and
becomes more turgid.
Q 26. If the kidney failure
cannot be treated by drugs or dialysis what advice is given to the patient?
Solution
In situation, where
kidney failure cannot be treated by drugs or dialysis, the patient is
advised for kidney transplantation. The donor for the kidney is preferably a
close relative of the patient as it reduces the chances of rejection.
Q 27. A women is feeling
breathlessness. What is done to help her to overcome
breathing problem?
Solution
She should be given
oxygen mask to facilitate breathing and in serious cases, patients are put on a
machine called ventilator.
Q 28. Explain the mechanism
of gaseous exchange during respiration.
Solution
1) In human beings,
alveoli in lungs provide a surface where the exchange of gases takes place.
2) Alveoli are surrounded by blood capillaries through which O2 diffuses
from alveoli to blood and from blood CO2 diffuses in lungs.
3) O2 further gets transported to all the cells in the
body.
Q 29. Major amount of water
is selectively reabsorbed by the tubular part of nephron in humans. What are
the factors on which the amount of water reabsorbed depends?
Solution
The amount of water
reabsorbed depends on : (i) The excessive amount of water present in the body.
(ii) The amount of dissolved wastes to be excreted out from the body.
Q 30. Two green plants are
kept separately in oxygen free containers, one in the dark and the other in
continuous light. Which one will live longer? Give reasons.
Solution
Plant kept
incontinuouslight will live longer, because it will be able to produce oxygen
reQ uired for its respiration
by the process of photosynthesis.
Q 31. Which instrument is
used to measure blood pressure?
Solution
Sphygmomanometer is used
to measure blood pressure
Q 32. A person is suffering
from dehydration. How do kidney help in conservation of water?
Solution
When water content is low
in body, the tubules of nephron in kidney absorb more water and ions and send
it back to the body to prevent dehydration.
Q 33. What is excretion?
How do unicellular organisms remove their wastes?
Solution
The biological process of
removing harmful metabolic wastes from the body is called excretion.
Unicellular organisms remove their wastes through simple diffusion.
Q 34. (a) Explain the
events which take place during photosynthesis. (b) Which test is done to prove
presence of starch in leaves?
Solution
(a)Photosynthesis takes
place in the following three steps: (i) Absorption of sunlight energy by
chlorophyll. (ii) Conversion of light energy into chemical energy, and
splitting of water into hydrogen and oxygen using light energy. (iii)
Reduction of carbon dioxide by hydrogen to form carbohydrate like glucose by
utilizing the chemical energy. (b) Iodine test is done to prove the presence of
starch in leaves. The starch present in leaves give blue-black colour with
iodine solution.
Q 35. Name the enzyme found
in saliva. State the role of saliva in the digestion of food.
Solution
Salivary amylase is the
enzyme found in saliva. Role of saliva : (1) Softening of food for easy
crushing by teeth. (2) It contains the enzyme ptyalin (salivary amylase ) that
convert starch into sugar. (Any one role)
Q 36. Suppose you went for
a marriage last night. When you reached home, you complained about acidity.
Explain the reason for acidity.
Solution
When we eat more food or
more spicy food, our digestive system has to work more by releasing more amount
of enzymes for digestion. Stomach releases more HCl to digest more food,
because of which a lot of acid is formed, which may lead to acidity. Acidity
can also cause diarrhoea, i.e. vomiting and loose motions.
Q 37. Suppose you hold your
breath. After maximum expiration for 10 sec, would there be any exchange of
respiratory gases occurring in lungs during the period? Give reason.
Solution
Yes, there will be
exchange of gases all the time because even after forceful respiration some
amount of air still remains in the lungs.
Q 38. In which form food is
transported in the plants?
Solution
Food is transported in
the plants in the form of sucrose.
Q 39. An extra cellular
fluid helps in the absorption of fat and production of antibodies. Name it and
write its function.
Solution
Lymph is an extra
cellular fluid which produces antibodies to fight against inflections. It also
helps in absorption of fat and drains excess fluid from extracellular space
into the blood.
Q 40. Explain the
significance of peristaltic movement that occurs all along the gut during
digestion.
Solution
It is necessary to move
the food in a regulated manner along the digestive tube so that it can be
processed properly in each part. The lining of canal has muscles that contract
rhythmically in order to push the food forward.
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