1. The kidneys in human beings are a part of the system for
(i) nutrition (ii) respiration
(iii)
excretion (iv)
transportation
Answer:
(iii)
Excretion
2. The xylem in plants are responsible for
(i) transport of water
(ii) transport of food
(iii) transport of amino acids
(iv) transport of oxygen
Answer:
(i) Transport
of water
3. The autotrophic mode of nutrition requires
(i)
carbon dioxide and
water
(ii) chlorophyll
(iii) sunlight
(iv) all of the above
Answer:
(iv) All of the
above
4. The breakdown of pyruvate to give carbon dioxide, water
and energy takes place in
(i)
cytoplasm
(ii) mitochondria
(iii) chloroplast
(iv) nucleus
Answer:
(ii)
Mitochondria
5. How are fats digested in our bodies? Where does this
process take place?
Answer:
Digestion of
fats takes place in the small intestine.
The bile salts present in the bile juice emulsify the fats. By this, large
globules break down into fine globules to provide larger surface area for the
enzyme action.
Lipase enzyme in the pancreatic juice digests the emulsified
fats. Lipase from intestinal juice converts fats into fatty acids and
glycerol.
6. What is the role of saliva in the digestion of food?
Answer:
Saliva
contains salivary amylase enzyme that breaks down starch into sugars
like maltose.
Saliva also helps
in chewing and breaking down the food.
7. What are the necessary conditions for autotrophic
nutrition and what are its by-products?
Answer:
· Presence of chlorophyll.
· Supply of water to green plants.
· Sufficient sunlight.
· Sufficient supply of CO2.
By-product of
autotropic nutrition is oxygen.
8. What are the differences between aerobic and anaerobic
respiration? Name some organisms that use the anaerobic mode of respiration.
Answer:
|
Aerobic respiration |
Anaerobic respiration |
|
Occurs
in presence O2. |
Occurs
in absence of O2. |
|
Complete
breakdown of food occurs. |
Partial
breakdown of food occurs. |
|
The
end products are CO2 and water. |
The
end products may be ethanol & CO2 or lactic acid. |
|
Produces
much energy. |
Produces
less energy. |
Organisms
that use anaerobic respiration are yeast, bacteria etc.
9. How are the alveoli designed to maximise the exchange of
gases?
Answer:
· Alveoli are balloon-like structures that increase surface area
for gas exchange.
· Alveoli are thin walled and richly supplied with a network
of blood vessels to facilitate gas exchange between blood and alveoli.
10. What would be the consequences of a deficiency of
haemoglobin in our bodies?
Answer:
Oxygen carrying
capacity decreases. As a result, the production of energy by oxidation will
become slower. It causes problems such as anaemia.
11. Describe double circulation in human beings. Why is it
necessary?
Answer:
In humans, blood goes through the heart twice during
each cycle. This is called double circulation. It is described as
follows:
· Oxygenated blood from
the lungs → left atrium relaxes →
blood enters left atrium → left atrium
contracts & left ventricle relaxes →
blood enters left ventricle → left ventricle
contracts → blood is pumped out to the body.
· Deoxygenated blood from the body → right atrium
relaxes → blood enters right atrium →
right atrium contracts & right ventricle dilates → blood transfers to right ventricle → right ventricle contracts →
blood is pumped into lungs for oxygenation.
Necessity
of double circulation: It
prevents mixing of deoxygenated and oxygenated blood. This ensures a highly
efficient supply of oxygen to the body. This is useful get energy to maintain
body temperature.
12. What are the differences between the transport of
materials in xylem and phloem?
Answer:
|
Xylem |
Phloem |
|
Conducts
water and dissolved minerals from roots to leaves. |
Conducts
prepared food material from leaves to other parts. |
|
Transport
of material takes place through vessels and tracheids. |
Transport
of material takes place through sieve tubes & companion cells. |
|
Upward
movement of water and dissolved minerals is mainly achieved by transpiration
pull. |
In
translocation, material is transferred into phloem tissue using energy from
ATP. This increases the osmotic pressure that moves the material in the
phloem to tissues. |
13. Compare the functioning of alveoli in the lungs and
nephrons in the kidneys with respect to their structure and functioning.
Answer:
|
Alveoli |
Nephron |
|
Functional
units of lungs. |
Functional
units of kidney. |
|
Alveoli
increase surface area for gas exchange. |
Long
and coiled tube of nephrons help in the reabsorption of filtrate. |
|
The
gas exchange of takes place through the network of capillaries in alveoli. |
The
Bowman’s capsule regulates the concentration of water and salts. |