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Science (Biology). Revision for Mid year Examination. Topics. Biological Molecules (Nutrients) Enzymes Nutrition in Man Nutrition in Plants. Biological Molecules (Nutrients). What are the components of the nutrients we need? Carbohydrate Fats Protein. Biological Molecules (Nutrients).

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Science biology

Science (Biology)

Revision for Mid year Examination


Topics

Topics

  • Biological Molecules (Nutrients)

  • Enzymes

  • Nutrition in Man

  • Nutrition in Plants


Biological molecules nutrients

Biological Molecules (Nutrients)

  • What are the components of the nutrients we need?

    Carbohydrate

    Fats

    Protein


Biological molecules nutrients1

Biological Molecules (Nutrients)

  • What are the function of these nutrients?


Biological molecules nutrients2

Biological Molecules (Nutrients)

  • How do we test for the nutrients?

    Food Test

  • Benedict’s Test

  • Starch Test

  • Emulsion Test

  • Biuret’s Test


Enzymes

Enzymes

What are enzymes?

Enzymes are biological catalysts that speed up the rate of reactionwithout themselves being chemically changed at the end of the reaction.


Enzymes1

Enzymes

Describe the effects of temperature on enzyme action.

  • At low temperature, enzymes are inactive.

  • Thus, little enzyme action.

  • As temperature increases, enzyme action also increases.


Enzymes2

Enzymes

  • Enzymes work best at their optimum

    temperature

  • Beyond their optimum temperature, enzymes are denatured.

  • Thus, enzyme action decreases.


Enzymes3

Enzymes

Describe the effects of pH on enzyme action.

  • Enzymes work best at their optimumpH.

  • At extremechanges in pH, enzymes are denatured.


Enzymes4

Enzymes

Explain the effects of temperature on enzyme action.

  • At low temperature, enzymes have very little kinetic energy and are inactive.

  • They move slowly and collide less frequently with the substrate molecules.

  • Substrate molecules bind to enzymes’ active siteless frequentlylittle enzyme action


Enzymes5

Enzymes

  • As temperature increases, enzymes gain more kinetic energy and moves around faster.

  • Thus, enzymes collide with the substrate moleculesmore frequently .

  • Substrate molecules bind to enzymes’ active sitemore frequently enzyme action increases.


Enzymes6

Enzymes

  • Enzymes work best at their optimum temperature.

  • Beyond their optimum temperature, active sites of the enzymes are physically altered.

  • Enzymes lose its specificity and can no longer bind the substrate.

  • Enzymes are denatured enzyme action decreases.


Enzymes7

Enzymes

Describe / Explain how enzymes work.

  • Enzymes work based on the lock and key hypothesis.

  • Enzymes are like the lock and substrates are the keys.

  • Enzymes have active sites which have a specific shape complementary to its substrate.


Enzymes8

Enzymes

  • Enzymes and substrate will collide.

  • Substrate will bind to the enzymes at the active site.

  • Products are then formed and released from the enzymes’ active site.


Enzymes9

Enzymes

  • Enzymes remain chemically unchanged at the end of the reaction.

    - Enzymes can then be reused.


Nutrition in man

Nutrition in Man

Describe / Explain the role of bile in digestion

  • bile is produced in the liver and secreted into the duodenum

  • bile emulsifies fats by breaking up fat droplets into smaller droplets

  • this increases the fats surface area for lipase to digest into fatty acids and glycerol


Nutrition in man1

Nutrition in Man

  • Describe the parts played in the digestion of food by

    (i) the pancreas

    (ii) the liver

    The pancreas:

  • pancreas secretes pancreatic juice into the duodenum

  • pancreatic juice contains amylase, trysinand lipase for digestion

  • pancreatic amylase will digest starch to maltose

  • trypsin digests proteins to polypeptides

  • pancreatic lipase digests fats into fatty acids and glycerol


Nutrition in man2

Nutrition in Man

  • the liver

  • the liver produces bile which aids in the digestion of fats

  • bile helps to emulsify the fats by breaking it up into smaller fat droplets

  • this increases the surface area for lipase to digest


Nutrition in man3

Nutrition in Man

  • thus, lipase can digest fats faster

  • liver plays a part in assimilation of glucose and amino acids

  • excess glucose is converted into glycogen by the hormone insulin


Nutrition in man4

Nutrition in Man

  • glycogen is stored in the liver

  • excess amino acids is deaminated whereby the amino group is removed

  • the remains of the amino acid is converted to glucose and excess glucose is converted to glycogen


Nutrition in man5

Nutrition in Man

  • normal amounts of glucose and amino acids will leave the liver via the hepatic vein

  • the glucose is used for respiration to produce energy

  • the amino acids is used for growth, repair of worn out tissues and synthesis of protoplasm


Nutrition in man6

Nutrition in Man

Describe what happens to fats as they pass through the following regions of the alimentary canal:

  • the mouth cavity

  • the duodenum

  • the rest of the small intestine

    the mouth cavity

    no fat digestion occurs in the mouth due to absence of lipase


Nutrition in man7

Nutrition in Man

(ii)the duodenum

  • bile produced in the liver is secreted into the duodenum

  • bile emulsifies fats by breaking it up into smaller fat droplets

  • this increases the surface area for lipase to digest into fatty acids and glycerol


Nutrition in man8

Nutrition in Man

  • the rest of the small intestine

  • in the ileum, the fatty acids and glycerol would be absorbed into the lacteals in the villi

  • villi are minute finger-like projections of the walls of the small intestinein the lacteal, fatty acids and glycerol recombines to form fats

  • fats will then be carried away by the lymphatic vessels


Science biology

Describe / Explain how the small intestine is adapted to carry out absorption of nutrients

The small intestine is adapted for absorption in three ways:

  • firstly, its inner walls are extensively folded to increase surface area for absorption

     secondly, its wall bears numerous villi

    villi are minute finger-like projections that increases the surface area for absorption

     thirdly, the small intestine is long and coiled to provide sufficient time for absorption


Science biology

Describe / Explain how the villi is adapted to carry out its function/s

  • Main function of villi is absorption of digested food substances

  • Villi is richly supplied with blood capillaries and lacteals

  • Glucose and amino acids are absorbed into the blood capillaries


Science biology

  • fats are absorbed into the lacteal

  • blood capillaries and lacteals carry away the absorbed food substances quickly

  • this maintains the concentration gradient for diffusion to occur

  • wall of the villi is also only one-cell thick

  • this provides a short diffusion distance for diffusion to occur faster


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