Question 9
How is the small intestine designed to absorb digested food?
Solution:
Small intestine has millions of tiny finger-like projections called villi. These villi
increase the absorbing surface of small intestine. The blood capillaries in villi
absorb digested food and carry it to the blood stream.
Question 10
What advantage over an aquatic organism does a terrestrial organism have with
regard to obtaining oxygen for respiration?
Solution:
Terrestrial organisms take up oxygen from atmosphere whereas aquatic animals
obtain oxygen from water. Air contains more O
2
as compared to water. Therefore,
terrestrial animals do not have to breathe quicker to get more oxygen. Therefore,
terrestrial organisms can facilitate better utilization of food by way of respiration.
Question 11
What are the different ways in which glucose is oxidised to provide energy in
various organisms?
Solution:
There are two types of respiration for oxidization of glucose.
Anaerobic Respiration: This process takes place in absence of oxygen. For
example, during yeast fermentation, pyruvate is converted into ethanol and
carbon dioxide.
Aerobic Respiration: In aerobic respiration, breakdown of pyruvate takes
place in presence of oxygen. Hence, optimum output of energy is achieved.
Question 12
How is oxygen and carbon dioxide transported in human beings?
Solution:
Transport of Oxygen: The respiratory pigment (haemoglobin) present in red
blood cell carry oxygen in blood. It carries oxygen to tissues which are deficient
in oxygen.