4 – Nutrition In Living Organisms
Q 1 Match the pairs :
(1) Group 'A' Group 'B'
Ans. (1) Parasitic plant - Cuscuta
(2) Insectivorous plant -
Drosera
(3) Saprophytic plant –
Mushroom
(4) Symbiotic plant -
Lichen
Q. 2. Classify according to food-type:
Tiger, cow, vulture, bacteria, deer, goat, human, fungus, lion,
sparrow, buffalo, frog, cockroach, tick.
Ans. Herbivores Carnivores
Omnivores Scavengers Decomposers Parasitic
Saprotrophic
Cow. Deer, Tiger,
Lion, Sparrow, Vulture Bacteria, Tick
Goat. Frog human, Fungus
Buffalo Cockroach
Q. 3. Answer the following questions in your own words:
(1) Why do living organisms need nutrition?
Ans. Living organisms need nutrition for the following reasons:
(1) For the continuous supply of energy to perform work. (2) To help in the
growth and development of the body. (3) To replace the worn out tissue and to
repair the damaged tissues. (4) To have resistance to infections and diseases.
(2) Explain the process of production of food in plants.
Ans. (1) The plants prepare the food by the process of
photosynthesis. Plants absorb water and minerals present in the soil with the
help of roots. (2) The carbon dioxide is taken from the air and with the help
of chlorophyll in the presence of sunlight, plant prepares glucose in the
process of photosynthesis. (3) In the process oxygen is liberated by the plant.
(4) Chemical reaction of the photosynthesis :
Carbon
dioxide + water Sunlight food (glucose) + oxygen
6 CO2 + 6H2O Chlorophyll C6H1206 + 602
(3) What is meant by parasitic plants? Name their different types
with examples of each.
Ans. (1) The plants that depend on other plants for their
nutrition are called parasitic plants. (2) The parasitic plants are
heterotrophic in their mode of nutrition. Some of them lack chlorophyll and
thus cannot perform photosynthesis on their own. (3) Loranthus is partial
parasite. It sucks the nutrition from its host but prepares its own food. (4)
Cuscuta or Dodder does not have chlorophyll. It looks yellow, wire like
climber. Hence it is complete parasite on the host tree.
(4) Explain the various steps of nutrition in animals.
Ans. There are main five steps of nutrition in animals, viz,
ingestion, digestion, absorption, assimilation and egestion.
(1) Ingestion : Feeding means ingestion. Food is taken in the body
in the process of ingestion
(2) Digestion : Different enzymes act on the complex food
constituents and convert these into soluble nutrients. This process takes place
nt the different places in the alimentary canal.
(3) Absorption : The
digested soluble nutrients are absorbed in the blood.
(4) Assimilation: The nutrients are taken to each cell and tissues
through the blood circulation. In the cells, energy is produced using these
nutrients. Once the energy is released then the food is said to be assimilated.
(6) Egestion : The matter that is not digested and absorbed is
thrown out of the body in the last step of egestion.
(5) Name some unicellular organisms in which all life-processes
take place within their unicellular body.
Ans. Amoeba, Euglena and
Paramoecium are the unicellular organisms in which all the life processes take
place within a single cell.
Q. 4. Give scientific reasons:
(1) Insectivorous plants are attractively coloured.
Ans. Insectivorous plants feed on insects. They need to capture
the insects. In order attract these insects towards the plant, 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. 7. Think and answer :
(1) We prepare a variety of foodstuffs and dishes at home. Are we
the autotrophic organisms?
Ans. (1) We prepare variety of foodstuffs by using grains, pulses,
vegetables, etc. (2) These provisions are given to us by plants. We may also
prepare food from flesh and eggs of other animals. (3) We cannot perform
photosynthesis wherein we can actually synthesize the food matter. (4) Hence we
are not autotrophs, we are heterotrophs.
(2) Which organisms are greater in number-autotrophs or
heterotrophs ? Why?
Ans. (1) The number of autotrophs is certainly more. The number of
plants should be more so that they can be enough for the herbivores. (2)
Herbivores are dependent upon autotrophs. (3) If autotrophs decrease in
numbers, the heterotrophs too will starve and die. (4) Therefore, in nature,
the autotrophs are always more than the heterotrophs to balance the food chain.
(3) The number of heterotrophs found in desert regions is smaller.
However, they are found in greater numbers in the sea. Why is this so?
Ans. (1) In desert region, the autotrophs are lesser in number as
well as heterotrophs dependent on them are also less. (2) The food is scarce,
therefore, the number of heterotrophs also reduces. (3) In oceans and seas
there are multitude of zooplankton and phytoplankton. Phytoplankton are very
small, microscopic floating plants which we may not see. (4) The food chain in
the seas is dependent on these planktonic species. Therefore, the number of
heterotrophs found in desert regions is smaller but they are found in greater
numbers in the sea.
(4) 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.
(5) 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. 9. Prepare and complete the flowchart according to type of
nutrition:
