Wednesday, 11 November 2015


1) The kidneys in human beings are a part of the system for
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.

ANSWER:-In human beings, the kidneys are a part of the system for excretion.

2) The xylem in plants are responsible for
(a) transport of water.
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.

ANSWER:-In a plant, the xylem is responsible for transport of water.

3) The autotrophic mode of nutrition requires
(a) carbon dioxide and water.
(b) chlorophyll.
(c) sunlight.
(d) all of the above.

ANSWER:-The autotrophic mode of nutrition requires carbon dioxide, water, chlorophyll and sunlight.

4 )The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus.

ANSWER:-The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

5) How are fats digested in our bodies? Where does this process take place?

ANSWER:-Fats are present in the form of large globules in the small intestine. The small intestine gets the secretions in the form of bile juice and pancreatic juice respectively from the liver and the pancreas. The bile salts (from the liver) break down the large fat globules into smaller globules so that the pancreatic enzymes can easily act on them.
The process takes place in the small intestine.

6) What is the role of saliva in the digestion of food?

ANSWER: - It moistens the food for easy swallowing. It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.

7) What are the necessary conditions for autotrophic nutrition and what are its by-products?

ANSWER:-Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. Carbohydrates and O2 are the by-products of photosynthesis.

8.) What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

ANSWER: - Parasitic worms, animal muscles use anaerobic mode of respiration.

Aerobic respiration
Anaerobic respiration
It occurs in the presence of O2.
It occurs in the absence of O2.
It involves the exchange of gases.
Exchange of gases is does not happen.
It occurs in cytoplasm and mitochondria.
It occurs only in cytoplasm.
It always releases CO2 and H2O.
End products vary

9) How are the alveoli designed to maximize the exchange of gases?

ANSWER:-The walls of the alveoli consist of extensive network of blood vessels. Each lung contains 300350 million alveoli, making it a total of approximately 700 million in both the lungs. The alveolar surface when spread out covers about 80 m2 area. This large surface area makes the gaseous exchange more efficient.

10) What would be the consequences of a deficiency of haemoglobin in our bodies?

ANSWER:-Deficiency of   haemoglobin in blood can affect the oxygen supplying capacity of blood. This can lead to deficiency of oxygen in the body cells. It can also lead to a disease called anemia.

11) Describe double circulation in human beings. Why is it necessary?

ANSWER:-Human heart is divided into four chambers the right atrium, the right ventricle, the left atrium, and the left ventricle.
Flow of blood in the heart:
The heart has superior and inferior vena cava, which carries de-oxygenated blood from the upper and lower regions of the body respectively and supplies this de-oxygenated blood to the right atrium of the heart.
The right atrium then contracts and passes the de-oxygenated blood to the right ventricle, through an auriculo-ventricular aperture.
Then the right ventricle contracts and passes the de-oxygenated blood into the two pulmonary arteries, which pumps it to the lungs where the blood becomes oxygenated.
From the lungs, the pulmonary veins transport the oxygenated blood to the left atrium of the heart.
Then the left atrium contracts and through the auriculo-ventricular aperture, the oxygenated blood enters the left ventricle.
The blood passes to aorta from the left ventricle. The aorta gives rise to many arteries that distribute the oxygenated blood to all the regions of the body.

12) What are the differences between the transport of materials in xylem and phloem?


Transport of materials in xylem
Transport of materials in phloem
Xylem tissue helps in the transport of water and minerals.
Phloem tissue helps in the transport of food.
Water is transported upwards from roots to aerial parts of plants
Food is transported in both upward and downward directions.
Transport in xylem requires physical forces such as transpiration pull.
Transport of food in phloem requires energy in the form of ATP.

13) Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.


(i) Alveoli are tiny balloon-like structurespresent inside the lungs.
(i) Nephrons are tubular structures present inside the kidneys.
(ii) The walls of the alveoli are one cell thick and it contains an extensive network of blood capillaries.
(ii) Nephrons are made of glomerulus, bowman’s capsule, and a long renal tube.
(i) The exchange of O2 and CO2 takes place between the blood of the capillaries that surround the alveoli and the gases present in the alveoli.
(i) The blood enters the kidneys through the renal artery. The blood is entered here and the nitrogenous waste in the form of urine is collected by collecting duct.
(ii) Alveoli are the site of gaseous exchange.
(ii) Nephrons are the basic filtration unit.