(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 ?
(a) The various organs of the human digestive system are mouth, oesophagus, stomach, small intestine and large intestine. The glands associated with the human digestive system are salivary glands, liver and pancreas.
(b) (i) Carbohydrates – The digestion of carbohydrates begins in the mouth. The human saliva contains an enzyme called salivary amylase which digests the starch present in the food into maltose sugar. The slightly digested carbohydrates when reaches the small intestine, pancreatic amylase present in the pancreatic juice breaks down the starch. The intestinal juice of the small intestine completes the digestion of carbohydrates and finally coverts it into glucose.
(ii) Fats – The process of digestion of fats begins in the stomach. The glands of stomach secrete a small amount of gastric lipase that breaks down the fats present in the food. From the stomach the partially digested food goes into small intestine where the pancreatic lipase breaks down the emulsified fats. The walls of small intestine secrete intestinal juice which converts the fats into fatty acids and glycerol.
(iii) Proteins – The digestion of proteins begins in the stomach. The glands of the stomach secrete gastric juice which contains an enzyme called pepsin. Pepsin converts the proteins into peptones. Pancreatic juice contains trypsin which digests the proteins into peptides and the intestinal juice completes the process of digestion of proteins thus converting it into amino acids.
(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.
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.