Class 10 Science Nutrition Exam Notes

Class 10 Science Nutrition Exam Notes. Please refer to the examination notes which you can use for preparing and revising for exams. These notes will help you to revise the concepts quickly and get good marks.

Nutrition

The process of intaking the food & utilization of food is called nutrition.

Nutrient :

The different component of food that have distinct functions like providing energy, materials for body building, maintenance & regulation of metabolism are called nutrient.

For example - Proteins, Minerals, Vitamin, Carbohydrates, fats.

Types Of Nutrient

Autotrophic Nutrition :

It is a mode of nutrition in which organisms are able to build up their own organic food from inorganic raw materials with the help of energy. The organism performing autotrophic nturtion are called autotrophs. (Gk. autos-self, trophe-nourishment). e.g., Ferrobacillus (iron bacterium).

Heterotrophic Nutrition  :

It is a mode of nutrition in which the organisms obtain readymade organic food from outside sources. The organisms that depend upon outside sources for obtaining organic nutritens are called heterotrophs. Heterotrophic nutrition is of three types - saprophytic, parasitic and holozoic.

Types Of Heterotrophic Nutrition 

Saprophytic or Saprotrophic Nutrition :

 It is a mode of heterotrophic nutrition in which food is obtained from organic remains like dead organisms, excreta, fallen leaves, broken twigs, food articles, etc. Organisms performing saprophytic nutrition are called saprophytes.

2. Parasitic Nutrition :

• It is a mode of hetrotrophic nutrition in which a living organisms flourishes by obtaining food from another living organism. The lving organisms which obtains food and shelter from another organism is called parasite. The organism which provides food and shelter to a parasite is known as host. An external plant parasite is Cuscuta (Amarbel). It is a non-green plant that sends haustroria or sucking roots into host plant for obtaining food and water.

3. Holozoic Nutrition :

• It is a mode of heterotrophic nutrition which involves intake of solid pieces of food. Since solid food is taken in, holozoic nutrition is also called ingestive nutrition. The food may consist of another animal, plant or its parts. Depending upon the source of food, holozoic organisms are of three types – Herbivores, carnivores, omnivores.

Herbivores :

• (L.herba-plant, vorare-to eat). They are holozoic organisms which feed on plants or plant parts, e.g., Cow, Buffalo, Deer, Goat, Rabbit, Grasshopper, Elephant, Squirrel, Hippopotamus.

 Carnivores :

• They are animals which feed on other animals. Carnivores are also called predators they hunt, kill and feed on their preys, e.g. Lion, Tiger, Leopard, Snake, Hawk.

Omnivores :

• (L.omnis-all, vorare-to eat). They are holozoic organisms which feed on both plant and animal materials, e.g. Cockroach, Ant, Pig, Crow, Rat, Bear, Dog, Humans.

Nutrition in Amoeba :

• Protozoan protests carry out holozoic nutrition through intracellular digestion.

(i) Ingestion :

Some protests can ingest food particle from any point on the surface (e.g., Amoeba) while others have fixed points for the same (e.g., Paramoecium). Protozoans like Amoeba capture food with the help of temporary finger-like processes called pseudopodia. Protozoans like (Paramoecium have small hair-like processes called cilia.) Beating of cilia creates current in water that pushes food particle through cytostome or cell mouth. The process of ingestion of solid food particle by a cell or unicellular organism is called phagocytosis.

• As soon as Amoeba comes in contact with a food particle or prey, it throws pseudopodia all around the same. The tips of encircling pseudopodia fuse and the prey comes to lie in a vesicle or phagosome. This method of intake of food is called circumvallation. Amoeba can also ingest food by other methods like import, circumfluence and invagination.

DIGESTIVE SYSTEM OF HUMA

Digestive system is a group of organs & associated digestive glands that take part in ingestion, digestive absorption of food & egestion of undigestible matter. Digestive organs from a continuous canal called alimentary canal.

ALIMENTARY CANAL CONTAINS FOLLOWING PARTS

Alimentary Canal in man is 9 metres long & consists of the following part

Mouth :
• Transverse slit like aperture.

Oral Cavity :

• It is bounded by lips & has cheeks, gums, teeth & tongue.
• The food taken inside oral cavity is masticated i.e. mechanically broken into smaller particles before being swallowed.
• The floor of the buccal cavity has a tongue bearing taste buds.
• Man possesses teeth on both the jaws, there are 32 teeth of four different types, namely incisors, canines, premolars & molars.

Dental Formula :

× 2 = x

No.of teeth in half part of upper jaw / No.of teethinhalf partof lower jaw × 2 = x

• In Man→ I2/2, C 1/1, Pm 2/2, M 3/3=8/8 x 2 = Total 32 teeths

Pharynx :
• It is short conical region that lies after the mouth cavity.

Oesophagous :
• It is a long narrow muscular tube which leads to the stomach. No digestive gland are present.

Stomach :
• It lies below the diaphragm on the left side of abdominal cavity is J-shaped.

Small Intestine :
• It is convoluted tube and differentiated into 3 regions, viz. Duodenum which is the first part of small intestine & is curved C-shaped; Jejunum, comparatively longer & more coiled and Ileum, which is the last part of small intestine whose inner surface is folded to form villi, which absorbs the products of digestion.

Large Intestine :
• It is much shorter & wider than small intestine & is differentiated into three regions viz;
• Caecum which is small rounded blind sac from which vermiform appendix arises;
• Colon is the inverted U-shaped tube
•  The rectum opens to exterior through anus.
•  No digestion takes place in large intestine, only absorption of water takes place.
•  In herbivores like horse, rabbit digestion of cellulose takes place in caecum.

 Absorption :
• In the small intestine (ileum) absorption of all digested materials takes place.

 Assimilation :
•  It is the process of utilisation of absorbed food for various body functions. The absorbed nutrients are utilised to resynthesise complex molecules like carbohydrates, protein & fats inside the cells.
• Man cannot digest cellulose.

 Egestion :
• It is the process of elimination of undigested food formed in the cells, or in the lumen of large intestine (colon & rectum) through the anus.
• Voluntary cotraction of abdominal muscles help in egestion of faeces.

TABLE : SUMMARY OF DIGESTION ENZYMES OF VARIOUS GLANDS WITH THEIR SECRETIONS AND END PRODUCTS OF DIGESTION IN MAN

NUTRITION IN PLANTS

Photosynthesis :
• Photosynthesis is the primary mode of food production in green plant. '' The process by which green plants synthesize food from simple substances carbon dioxide and water in the presence of sunlight is called Photosynthesis''

• The process of photosynthesis can be represented in the form of chemical reaction, as given below :
6CO2 + 12H2O → C₆H₁₂O₆ + 6H₂O + 6O₂
Carbon Water Glucose Water Oxygen dioxide

 Photosynthetic Pigment :
• The light energy must be absorbed by a suitable pigment i.e. chlorophyll (green pigment).
• Chlorophyll is green colour pigment.

 Mechanism of Photosynthesis :
• Photosynthesis is divided in 2 main steps
(A) light reaction (B) dark reaction

 Light reaction :
• It is also called Hill Reaction.
• It occurs in grana of thylakoids.
• It is named as light reaction as it occurs only in presence of light.

Major Step :
• Absorption of light by chlorophyll.
• Photolysis of water.
• Reduction of CO2 to Carbohydrates.
• In this process ADP changes to ATP & inorganic phosphate.
• Release of oxygen into atmosphere.

Opening and Closing Stomata :
• The opening and closing of stomata depend upon the turgid or flaccid state of the guard

cells. When guard cells are in turgid state the stomatal aperture opens and when guard cells are in flaccid state the stomatal aperture closes. The inner wall of guard cells (towards pore) is thick and outer wall(towards other epidermal cells) is thin. When the turgor pressure of the guard cells is increased the outer thinner wall of the guard cell is pushed out (towards the periphery) due to which a tension is created on the inner thicker wall thus pulling the inner thicker wall towards the periphery thus leading to the opening of stomatal aperture. On the contrary when the guard cells are in a flaccid state the outer thinner wall of guard cells returns to original position (moves towards pore) due to which tension on the inner wall is released which also returns to its original position and stomatal aperture gets closed again.

 Dark Reaction :
• This reaction is not dependent on light. It is also known as calvin – Benson Cycle or C3 cycle as first stable product is phosphogliceric acid (PGA) a 3 carbon compound.

 C4 Cycle or Hatch & Slakcycle :
• 4-C compound i.e. oxaloacetic acid (OAA).
• This cycle is found in many other tropical & subtropical monocots eg : Maize, Sorghum , Wheat, Oat, Pearl, millet etc.
•  In dicots also many such plants are known eg : Amaranthus, Chenopodium, Atriplex, Euphorbia etc. In some families of dicots Compositae, Portulaceae, Nyctaginaceae.

 Crassulacean Acid Metabolism (CAM) :
• Certain plants, especially succulents which grow under extremely xeric (dry) condition, fix atmospheric CO2 in dark.
• Since the process was first observed in the plants belonging to family crassulaceae (eg. Bryophyllum, kalanchoe etc.) It was termed crassulacean acid metabolism (CAM).
• The most characteristic feature of these plants is that their stomata remain open at night (in dark) but closed during the day (in light).
• Thus, CAM is a kind of adaptation in succulents to carry out photosynthesis without much loss of water

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