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For example amoeba [fig-9(a)] takes in food using
temporary finger like extensions (pseudopodia) of the cell
Food
vacuole surface which fuse over the food particle forming food vacuole.
Inside the food vacuole, complex substances are broken down
into simpler ones. Then diffuse into the cytoplasm. The
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Oral remaining undigested material is moved to the surface of the
groove
cell and thrown out. In Paramoecium [fig-9(b)], which is also a
Formation
of food
unicellular organism the cell has a definite shape. Food is taken
vacuole
in at a specific spot. Food is moved to the spot by the movement
Anal pore of cilia which covers the entire surface of the cell, where the
food is ingested (cytostome).
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12 X Class Nutrition - Food supplying system
Parasitic nutrition in Cuscuta
Dodder (genus Cuscuta) is a leafless, twining, parasitic plant
belongs to morning glory family (Convolvulaceae). The genus
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contains about 170 twining species that are widely distributed
throughout the temperate and tropical regions of the world.
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fig-10: Haustoria
The dodder plant contains no chlorophyll. Cuscuta reflexa
in cuscuta
has been found to have very little amount of chlorophyll and instead absorbs
food through haustoria. They are root like structures that penetrate the tissue
of a host plant and may kill it. The slender, string like stems of the dodder
may be yellow, orange, pink, or brown in colour. It’s leaves are reduced to
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minute scales. The dodder’s flowers, in nodule like clusters, are made up of
tiny yellow or white bell-like petals.
The dodder’s seed germinates, forming an anchoring root, and then
sends up a slender stem that grows in a spiral fashion until it reaches a
host plant. It then twines around the stem of the host plant and forms
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haustoria, which penetrate through it. Water is drawn through the haustoria
from the host plant’s xylem, and nutrients are drawn from its phloem.
Meanwhile, the root rots away after contact has been made with a host
stem. As the dodder grows, it sends out new haustoria (parasitic roots) and
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establishes itself very firmly on the host plant. After growing in a few
spirals around one host shoot, the dodder finds its way to another, and it
continues to twine and branch until it resembles a fine, densely tangled
web of thin stems enveloping the host plant. Identify plants in your
surroundings which are parasitic on other plants.
Nutrition in Human Beings
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Human digestive system is very
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complex in nature. Different parts are Mouth
Salivary gland
involved and perform different functions by
using various digestive juices and enzymes. Oesophagus
Stomach
Let us observe the figure of digestive
Pancreas
system. Liver
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The alimentary canal is basically a long
tube extending from the mouth to the anus.
We can see that this tube has different parts. Large intestine
Various regions are specialized to perform Small intestine
different functions.
Rectum
What happens to the food once it enters Anus
our body? fig-11: Alimentary canal of man
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