Explain why, when air is taken in and let out during breathing, the lungs always contain a residual volume of air.
During the breathing cycle, when air is taken in and let out, the lungs always contain a certain residual volume of air so that there is sufficient time ‘for the oxygen absorbed’ into the blood and ‘for the carbon dioxide to be released’ from the blood.
(a) Name the pigment in leaves which absorbs sunlight energy.
(b) What is the colour of this pigment ?
Name the green dot like structures in some cells observed by a student when a leaf peel was viewed under a microscope. What is this green colour due to?
What is the name of those cells in the leaf of a plant which control the opening and closing of stomata?
Name the enzyme present in human saliva. What type of food material is digested by this enzyme ?
Apart from sunlight and chlorophyll, what other things are required to make food by photosynthesis ?
a) How do plants obtain food ?
(b) Why do plants need nitrogen ? How do plants obtain nitrogen ?
Name one substance which is produced in anaerobic respiration by an organism but not in aerobic respiration.
Draw a neat diagram of excretory system of human beings and label the following:
(i) Kidney
(ii) Ureter
(iii) Urinary Bladder
(iv) Urethra
A Give one reason why multicellular organisms require special organs for exchange of gases between their body and their environment. :
In addition to carbon dioxide and water, state two other conditions necessary for the process of photosynthesis to take place.
What is the name of tiny projections on the inner surface of small intestine which help in absorbing the digested food ?
(a) What are heterotrophs ? Give one example of heterotrophs.
(b) What is the difference between autotrophic nutrition and heterotrophic nutrition ?
(a) Which part of the body secretes bile ? Where is bile stored ? What is the function of bile ?
(b) What is trypsin ? What is its function ?
Name the following :
(a) The process in plants which converts light energy into chemical energy.
(b) Organisms that cannot prepare their own food.
(c) Organisms that can prepare their own food.
(d) The cell organelle where photosynthesis occurs.
(e) The cells which surround a stomatal pore.
(f) An enzyme secreted by gastric glands in stomach which acts on proteins.
What are the different ways in which glucose is oxidised to provide energy in various organisms ? Give one example of each.
What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.