PLANTHORMONE |
FUNCTIONS |
Auxins |
Promote cell enlargement and cell differentiation. Promote fruit growth. (responsible for phototropic and geotropic responses in plants). |
Gibberellins |
Promote cell enlargement and cell differentiation in the presence of auxins. Promote fruit growth. Help in breaking dormancy of seeds and buds. |
Cytokinins |
Promote cell division. Promote fruit growth. Help in breaking dormancy of seeds and buds. Delay the ageing in leaves. Promote opening of stomata. |
Abscisic acid (ABA, growth inhibitor) |
Promote the dormancy of seeds and buds. Promote closing of stomata. Promote the wilting and falling of leaves. |
Exocrine glands |
Endocrine glands |
A gland which secretes its product into a duct or tube is called exocrine gland. |
A gland which does not have a duct & secretes its product directly into blood stream is called endocrine gland. |
Eg. Salivary gland secretes saliva into a duct called salivary duct. |
Eg. Pituitary gland, thyroid gland. |
Name of the gland |
Location |
Hormone secreted |
Functions |
Deficiency or excess |
Hypothalamus |
Present in brain |
Produces ‘releasing hormones’ and ‘inhibitory hormones’ |
Regulate the secretion of hormones from pituitary gland |
|
Pituitary gland (master gland) |
Present just below the brain |
Secretes several enzymes for ex. Growth hormone (HGH) |
Controls the development of bones and muscles. |
Deficiency of growth hormone in childhood leads to dwarfism and excess leads to gigantism (giantness) |
Thyroid gland |
Attached to wind pipe |
Thyroxine (contains iodine) |
Control the rate of metabolism of fats, proteins and carbohydrates. |
Deficiency of thyroxine causes goiter. |
Parathyroid |
Four parathyroid glands embedded in thyroid gland. |
Parathormone |
Regulate calcium and phosphate level in blood. |
|
Thymus |
Lower part of neck and upper part of chest |
Thymus hormone |
Plays a role in development of immune system in the body. |
Note: it is larger in young children but shrink after puberty |
Pancreas (both exocrine and endocrine) |
Just below the stomach |
Insulin and glucagon |
Control blood sugar level. Insulin: lowers blood sugar level. Glucagon: higher blood sugar level. |
Deficiency of insulin causes diabetes. |
Adrenal (both exocrine and endocrine) |
Located on the top of two kidney |
Adrenaline hormone |
Regulate heart beat, breathing rate, blood pressure and carbohydrate metabolism. |
Note: it is also known as gland of emergency. |
Testes (present only in males) |
Outside the abdominal cavity within the scrotum |
Male sex hormone i.e. testosterone |
Control development of male sex organ and male sex features such as deeper voice, beard etc. Also makes the male gamete sperms. |
|
Ovary |
Present only in females |
Female sex hormones i.e. oestrogen and progesterone |
Oestrogen: control the development of female sex organ and female sex features such as feminine voice, soft skin, mammary glands etc. Progesterone: maintaining the pregnancy. Control the uterus changing during menstrual cycle. Ovaries make the female gamete called ova or egg. |
|
The radicals at first grow in a downward direction due to the effect of gravity (positive geotropism), but after some time, the roots bend toward the moist soil (positive hydrotropism). This is evidently due to the closeness of the germinating roots to water.