give description of plant and animal hormone?
Asked by Meenu S Unnithan
| 18th Sep, 2014,
08:31: AM
Plant Hormones: Plant hormones control some aspects of the growth of plants such as cell division, cell enlargement and cell differentiation.
Phytohormones
Description
1. Auxins
- Promote growth of plants.
- They are secreted by the cells present at the tip of stems and roots.
- Therefore, auxins control the phototropic and geotropic movements of plants.
- Auxins accelerate growth of stems but reduce the growth in roots.
- Synthetic auxins are used in horticulture.
2. Gibberellins
- Promote cell differentiation in the presence of auxins.
- They break seed dormancy.
- They also break dormancy in buds.
- Stimulate elongation of shoots.
3. Cytokinins
- Promote cell division in plants.
- Delay ageing of leaves.
- Promote opening of stomata.
- Promote fruit growth.
4. Abscisic Acid
- Acts as a growth inhibitor.
- It promotes dormancy in seeds and buds.
- Promotes closing of stomata.
- Promotes abscission, i.e. wilting and falling of leaves.
- Detachment of flowers and fruits from the plants is due to abscisic acid.
Hormones in Animals: They are secreted by different endocrine glands.
Hormones
Functions
Disorders
1. Adrenaline
Produced by the adrenal glands.
- Adrenaline prepares the body for the fight and flight mechanism.
- When excited or in anger, the adrenal glands produce a lot of adrenaline.
- It speeds up heart beat and breathing.
- It raises the blood pressure.
- Blood supply to the digestive system and skin is reduced, and the blood supply to the skeletal muscles is increased.
2. Thyroxine
Secreted by the thyroid gland.
- Regulates carbohydrate, protein and fat metabolism.
- It increases the basal metabolic rate (BMR).
- It regulates body growth such as ossification of bones and mental development.
Simple goitre:
- It is caused by iodine deficiency.
- Iodine is necessary for the synthesis of thyroxine.
- In this disorder, the gland is enlarged which is prominent due to swelling in the neck.
3. Growth Hormone (Somatotropin)
Secreted by the anterior lobe of the pituitary gland.
- It is essential for normal growth.
Dwarfism:
- Due to the deficiency of growth hormone.
- The growth of bones and other body organs is slow.
Gigantism:
- Due to the oversecretion of growth hormone.
- The bones grow long.
- Such a person giants up to 2.7 metre in height.
4. Insulin
Secreted by pancreas
- Regulates the blood glucose (sugar) level.
Diabetes Mellitus
Symptoms:
- High concentration of sugar in blood (hyperglycemia).
- Excretes large amount of urine containing more concentration of sugar.
- A person feels thirsty due to constant loss of water through urination.
- The person loses weight and becomes weaker.
- Sometimes, the person may lose vision.
Treatment:
It cannot be cured, but sugar levels can be maintained by the administration of insulin.
5. Testosterone
Secreted by the testes in males.
- Controls the development of sex organs in males.
- Controls the development of secondary sexual characters during puberty.
6. Oestrogen
Secreted by the ovaries in females.
- Controls the development of female sex organs.
- Controls the development of secondary sexual characters during puberty in females.
Plant Hormones: Plant hormones control some aspects of the growth of plants such as cell division, cell enlargement and cell differentiation.
Phytohormones |
Description |
1. Auxins |
|
2. Gibberellins |
|
3. Cytokinins |
|
4. Abscisic Acid |
|
Hormones |
Functions |
Disorders |
1. Adrenaline Produced by the adrenal glands. |
|
|
2. Thyroxine Secreted by the thyroid gland. |
|
Simple goitre:
|
3. Growth Hormone (Somatotropin) Secreted by the anterior lobe of the pituitary gland. |
|
Dwarfism:
Gigantism:
|
4. Insulin Secreted by pancreas |
|
Diabetes Mellitus Symptoms:
Treatment: It cannot be cured, but sugar levels can be maintained by the administration of insulin. |
5. Testosterone Secreted by the testes in males. |
|
|
6. Oestrogen Secreted by the ovaries in females. |
|
|
Answered by Hemangi Binny
| 18th Sep, 2014,
09:20: AM
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