Describe the process of respiration in the following parts of a plant :
(a) Root (b) Stem (c) Leaves
(a) Respiration in roots: The roots of a plant take the oxygen required for respiration from the air present in-between the soil particles by the process of diffusion. The roots have extensions of epidermal cells of a root called root hair which are in contact with the air in the soil. Oxygen diffuses from root hairs and reaches all the other cells of the root for respiration. Carbon dioxide gas produced in the cells of the root during respiration moves out through the root hairs by the process of diffusion. Thus, the respiration in roots occurs by diffusion of respiratory gases through the root hairs.
(b) Respiration in stems: The stems of herbaceous plants takes place through stomata. The oxygen from the air diffuses into the stem of a herbaceous plant through stomata and reaches all the cells for respiration. The carbon dioxide produced diffuses out through stomata. In woody stems, the bark has lenticels for the exchange of gases.
(c) Respiration in leaves: The leaves of a plant has tiny pores called stomata through which the exchange of respiratory gases takes place by diffusion. Oxygen from air diffuses into a leaf through stomata and reaches all the cells, where it is used for respiration and the carbon dioxide produced diffuses out from the leaf into the air through stomata.
(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 scientific name of the animals which are :
(i) only meat eaters ?
(ii) only plant eaters ?
(iii) both, plant and meat eaters ?
What is the name of tiny projections on the inner surface of small intestine which help in absorbing the digested food ?
(a) What criteria can be used to decide whether something is alive ?
(b) What is meant by life processes ? Name the basic life processes common to all living organisms which are essential for maintaining life.
(a) What are heterotrophs ? Give one example of heterotrophs.
(b) What is the difference between autotrophic nutrition and heterotrophic nutrition ?
(a) What is the role of hydrochloric acid in our stomach ?
(b) What is the function of enzymes in the human digestive system ?
(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.
(a) Name the main organs of the human digestive system. Also name the associated glands.
(b) How do carbohydrates, fats and proteins get digested in human beings ?
What are the different ways in which glucose is oxidised to provide energy in various organisms ? Give one example of each.
Explain why, when air is taken in and let out during breathing, the lungs always contain a residual volume of air.
What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.