4.
NUTRITION IN LIVING ORGANISMS
(1) What is malnutrition?
Ans. Malnutrition is the state when the required nutrients for proper functioning of the body are not obtained
through the diet.
(2) Which are the ways to prevent malnutrition?
Ans. Taking wholesome food and balanced diet is the way to prevent malnutrition.
Q. Give scientific reasons :
(1) Insectivorous plants are attractively coloured.
Ans. Insectivorous plants feed on insects. They need to capture the insects. In order to attract these insects, they
are attractively coloured.
(2) Butterflies have a long tube-like proboscis.
Ans. Every insect is provided with mouth parts for ingestion. It feeds on nectar and pollen from the flowers. It
thus has a tube like proboscis to suck this food from flower.
Q. Think and answer :
(1) We prepare a variety of foodstuffs and dishes at home. Are we then autotrophic organisms?
Ans. (1) We prepare variety of foodstuffs by using grains, pulses, vegetables etc. (2) These provisions are given to
us by plants. (3) We cannot perform photosynthesis. (4) Hence we are not autotrophs, we are heterotrophs.
(2) Which organisms are greater in number-autotrophs or heterotrophs? Why?
Ans. The number of autotrophs is certainly more. The number of plants should be more so that they can be enough
for the herbivores.
(3) Why is plant food not produced in any other parts of the plant except the green ones?
Ans. The chlorophyll is present in the green parts of the plants. In these parts photosynthesis takes place. This
produces food. The non-green parts do not produce food due to lack of chlorophyll.
(4) What damage or harm do ectoparasitic and endoparasitic animals cause?
Ans. (1) Parasitic organisms depend on the host for its nutrition. (2) Ectoparasites have specialized mouth parts.
With the help of these, they suck the blood. e.g. mosquito and bed bugs. The biting insects cause a lot of
discomfort. (3) Mosquitoes spread many diseases such as malaria, dengue and elephantiasis. (4)
Endoparasites live inside the body of host. e.g., Round worm, hook worm, pin worm etc. (5) They absorb
host's nutrients and cause malnourishment to the host. Both ectoparasites and endoparasites cause damage to
our health.
Q. Use your brain power!
(1) Which part of the Loranthus plant carries out photosynthesis?
Ans. Leaves of Loranthus carries out photosynthesis.
(2) From where do they obtain minerals and water?
Ans. Loranthus obtains the necessary minerals and water from the host plant. For absorption of these nutrients
there are specialized roots which are inserted into xylem of the in flower.
(3) Why is Loranthus known as a partially parasitic plant?
Ans. Loranthus takes shelter on the host tree. It sucks the water and minerals from the host. But it can
photosynthesize and prepare its own food. Therefore, it is called a partial parasite.
(4) Why does the pitcher plant feed on insects even though it produces food by photosynthesis?
Ans. Pitcher plant grows in the soil that is deficient on nitrogen. Plant requires nitrogen for building up proteins.
To overcome this problem, pitcher plant feed on insects.
(5) How does photosynthesis occur in dark red or purple coloured leaves?
Ans. In coloured plants, there are carotenoids, xanthophyll and anthocyanins which gives reddish, yellow and
purple colours respectively. These plants also have chlorophyll besides these coloured pigments. However,
due to extra coloured pigments these plants appear to be of that colour and not green. Photosynthesis in such
plants also occur due to chlorophyll.
(6) What is chemosynthesis? Which plants produce their food by chemo-synthesis?
Ans. (1) Using carbon dioxide, methane, hydrogen, hydrogen sulfide etc. as the sources of energy and producing
food in this process is called chemosynthesis. (2) Only bacteria (microbes) residing in the areas where
sunlight does not reach, perform chemosynthesis.
