Plant And Animal Hormone Flashcards
There are five major classes of plant hormones.
They are:
- Auxins
- Cytokinins
- Gibberellins
- Abscisic Acid (ABA)
- Ethylene
Among all these plant hormones ________ promote plant growth while __________ inhibit plant growth.
auxins, cytokinins and gibberellins
abscisic acid and ethylene
were the first plant hormones discovered.
Auxins (Gk. auxein = to grow)
The term auxin was introduced by
Kogl and Haagen- Smith (1931).
Auxins are produced at the tip of ______ from where they migrate to the zone of elongation
stems and roots
,who observed unilateral growth and curvature of canary grass (Phalaris canariensis) coleoptiles. He came to the conclusion that some ‘influence’ was transmitted from the tip of the coleoptile to the basal region
Charles Darwin (1880)
This ‘influence’ was later identified as Auxin by Went.
________ a Dutch biologist demonstrated the existence and effect of auxin in plants. He did a series of experiments in Avena coleoptiles
Frits Warmolt Went (1903-1990),
Types of Auxins: Auxins are classified into two types, namely
- Natural Auxins: Auxins produced by the plants are called natural auxins. Example: IAA (Indole-3- Acetic Acid)
- Synthetic Auxins: Artificially synthesized 15.1.2 C auxins that have properties like auxins are called as synthetic auxins. Example: 2,4D (2,4 Dichlorophenoxy Acetic Acid
______ promote the elongation of stems and coleoptiles which makes them to grow
Auxins
_______ induce root formation at low concentration and inhibit it at higher concentration.
Auxins
The auxins produced by the apical buds suppress growth of lateral buds. This is called
apical dominance
Seedless fruits without fertilization are induced by the external application of auxins. (___________) Examples: Watermelon, Grapes, Lime etc.
Parthenocarpy
Auxins prevent the formation of
abscission layer.உதிர்தல்
Phenyl Acetic Acid (PAA) and
Indole 3 Acetonitrile (IAN) are natural auxins.
Indole 3 Butyric Acid (IBA),
Indole-3- Propionic Acid, a-Naphthalene Acetic Acid (NAA),
2, 4, 5-T (2,4,5 Trichlorophenoxy Acetic Acid)
are some of the synthetic auxins
Cytokinin is found abundantly in liquid endosperm of .
coconut
Cytokinins (Cytos - cell; kinesis - division) are the plant hormones that __________or cytokinesis in plant cells
promote cell division
cytokinin was first isolated from ________
Herring fish sperm.
was the cytokinin isolated from Zea mays(makkacholam)
Zeatin
Morphogenesis
Both auxins and cytokinins are essential for the formation of new organs from the callus in tissue culture
Cytokinin induces cell division (cytokinesis) in the
presence of auxins.
Cytokinins promote the growth of ______ even in the presence of apical bud
lateral buds
Richmond Lang effect
Application of cytokinin delays the process of ageing in plants. This is called Richmond Lang effect.
Gibberellins are the most abundantly found plant hormones. _______ observed Bakanae disease or foolish seedling disease in rice crops
internodal elongation in rice was caused by fungus Gibberella fujikuroi. The active substance was identified as _______
Kurosawa (1926)
Gibberellic acid.
Application of gibberellins on plants stimulate extraordinary ________ e.g. Corn and Pea.
elongation of internode.
bolting
Treatment of rosette plants with gibberellin induces sudden shoot elongation followed by flowering. This is called bolting.
____ promote the production of male flowers in monoecious plants (Cucurbits).
Gibberellins
Gibberellins of potato tubers.
break dormancy
Gibberellins are efficient than auxins in inducing the formation of seedless fruit Parthenocarpic fruits (Development of fruits without fertilization) e.g. _____.
Tomato
Abscisic acid (ABA) is a growth inhibitor which regulates abscission and dormancy. of plants.
Abscisic acid increases tolerance of plants to various kinds of stress. So, it is also called as ________. It is found in the chloroplast
stress hormone
ABA promotes the process of ______(separation of leaves, flowers and fruits from the branch).
2.
abscission
During water stress and drought conditions ABA causes
stomatal closure.
ABA promotes senescence in leaves by causing loss of
chlorophyll
ABA induces _____ towards the approach of winter in trees like birch.
bud dormancy
ABA is a powerful inhibitor of ________ growth in tomato.
lateral bud
Ethylene is a _______plant hormone. It is a _______. It is mainly concerned with maturation and ripening of fruits. Maximum synthesis of ethylene occurs during ripening of fruits like apples, bananas and melons
gaseous
growth inhibitor
Physiological effects of ethylene
- Ethylene promotes the ripening of fruits. e.g. Tomato, Apple, Mango, Banana, etc.
- Ethylene inhibits the elongation of stem and root in dicots.
- Ethylene hastens the senescence of leaves and flowers.
- Ethylene 49 abscission stimulates formation of zone in leaves, flowers and fruits. This leads to premature shedding.
- Ethylene breaks the dormancy of buds, seeds and storage organs.
The branch of biology which deals with the study of the endocrine glands and its physiology is known as .
endocrinology
is of known as Father of Endocrinology.
Thomas Addison
English physiologists _______ introduced the term hormone in _____. They first discovered the hormone _______.
W.M Bayliss and E. H. Starling
1909
secretin
Exocrine glands have specific ducts to carry their secretions e.g.
salivary glands, mammary glands, sweat glands
Endocrine glands present in human and other vertebrates are
a. Pituitary gland
b. Thyroid gland
c. Parathyroid gland
d. Pancreas (Islets of Langerhans)
e. Adrenal gland (Adrenal cortex and Adrenal medulla)
f. Gonads(Testes and Ovary)
g. Thymus gland
The pituitary gland or _______ is a pea shaped compact mass of cells located at the base of the midbrain attached to the hypothalamus by a pituitary stalk.
hypophysis
They are the anterior lobe (_____) and the posterior lobe (______). The intermediate lobe is non-existent in humans.
adenohypophysis
neurohypophysis
The pituitary gland forms the major endocrine gland in most vertebrates. It regulates and controls other endocrine glands and so is called as the “”.
Master gland
Hormones secreted by the anterior lobe (Adenohypophysis) of pituitary
a. Growth Hormone
b. Thyroid stimulating Hormone
c. Adrenocorticotropic Hormone
d. Gonadotropic Hormone which comprises the Follicle Stimulating Hormone and Luteinizing Hormone
e. Prolactin
GH promotes the development and enlargement of all tissues of the body.
It stimulates the growth of muscles, cartilage and long bones. It controls the cell metabolism
Dwarfism
. It is caused by decreased secretion of growth hormone in children. The characteristic features are stunted growth, delayed skeletal formation and mental disability
Gigantism
: Oversecretion of growth hormone leads to gigantism in children. It is characterised by overgrowth of all body tissues and organs. Individuals attain abnormal increase in height
Acromegaly:
Excess secretion of growth hormone in adults may lead to abnormal enlargement of head, face, hands and feet.
Thyroid stimulating hormone (TSH)
TSH controls the
growth of thyroid gland, coordinates its activities and hormone secretion.
Adrenocorticotropic hormone (ACTH)
ACTH stimulates adrenal cortex of the adrenal gland for the production of its hormones.
It also influences protein synthesis in the adrenal cortex
Gonadotropic hormones (GTH)
The gonadotropic hormones are _______ which are essential for the normal development of gonads.
follicle stimulating hormone and luteinizing hormone
Follicle stimulating hormone (FSH)
In male, it stimulates the germinal epithelium of testes for formation of sperms.
In female it initiates the growth of ovarian follicles and its development in ovary.
Luteinizing hormone (LH)
In male, it promotes the Leydig cells of the testes to secrete male sex hormone testosterone. ,
In female, it causes ovulation (rupture of mature graafian follicle), responsible for the development of corpus luteum and production of female sex hormones estrogen and progesterone
Prolactin (PRL)
PRL is also called .
lactogenic hormone
______ hormone initiates development of mammary glands during pregnancy and stimulates the production of milk after child birth.
Prolactin
Melatonin is a hormone produced by the pineal gland. It is known as a ‘time messenger. It signals night time information throughout the body.
Exposure to light at night, especially short-wavelength light, can decrease melatonin production interrupting sleep. Suppression of melatonin has been implicated in sleep disturbances and related metabolic disorders.
The hormones secreted by the posterior Triiodot pituitary are
a. Vasopressin or Antidiuretic hormone
b. Oxytocin
Vasopressin or Antidiuretic hormone (ADH)
In kidney tubules it increases reabsorption of water. It reduces loss of water through urine and hence the name antidiuretic hormone.
Deficiency of ADH
Antidiuretic hormone
reduces reabsorption of water and causes an increase in urine output (polyuria). This deficiency disorder is called Diabetes insipidus.
Oxytocin
It helps in the contraction of the smooth muscles of uterus at the time of child birth and milk ejection from the mammary gland after child birth.
The thyroid gland is composed of two distinct lobes lying one on either side of the trachea. The two lobes are connected by means of a narrow band of tissue known as the
isthmus
This gland is composed of glandular follicles and lined by cuboidal epithelium. The follicles are filled with colloid material called
thyroglobulin
An amino acid _________ are involved in the formation of thyroid hormone. The hormones secreted by the thyroid gland are
tyrosine and iodine
a. Triiodothyronine (T3)
b. Tetraiodothyronine or Thyroxine (T4)
The functions of thyroid hormones are
◆ Production of energy by maintaining the Basal Metabolic Rate (BMR) of the body
* Helps to maintain normal body temperature.
◆ Influences the activity of central nervous system.
* Controls growth of the body and bone formation.
* Essential for normal physical, mental and personality development
* It is also known as personality hormone.
* Regulates cell metabolism
_____ first crystallised thyroxine hormone.
Edward C. Kendal in 1914
Thyroid gland requires “_______ everyday for the production of thyroxine.
120 µg” of iodine
_______ identified the molecular structure of thyroxine in _____.
Charles Harrington and George Barger
1927
When the thyroid gland fails to secrete the normal level of hormones, the condition is called
thyroid dysfunction.
It is caused due to the decreased secretion of the thyroid hormones. The abnormal conditions are simple goitre, cretinism and myxoedema
Hypothyroidism
It is caused due to the inadequate supply of iodine in our diet. This is commonly prevalent in Himalayan regions due to low level of iodine content in the soil. It leads to the enlargement of thyroid gland which protrudes as a marked swelling in the neck and is called as .
goitre
It is caused due to decreased secretion of the thyroid hormones in children. The conditions are stunted growth, mental defect, lack of skeletal development and deformed bones. They are called as
cretins(cretinism)
It is caused by deficiency of thyroid hormones in adults. They are mentally sluggish, increase in body weight, puffiness of the face and hand, oedematous appearance.
Myxoedema
Hyperthyroidism
The symptoms are protrusion of the eyeballs (Exopthalmia), increased metabolic rate, high body temperature, profuse sweating, loss of body weight and nervousness.
It is caused due to the excess secretion of the thyroid hormones which leads to Grave’s disease( Exopthalmia goitre).
Hypothyroidism
The parathyroid glands are ________that are situated on the posterior surface of the thyroid lobes
four small oval bodies
The chief cells of the gland are mainly concerned with secretion of .
parathormone
Functions of Parathormone
The parathormone regulates calcium and phosphorus metabolism in the body. They act on bone, kidney and intestine to maintain blood calcium levels.
Removal of parathyroid glands during thyroidectomy (removal of thyroid) causes decreased secretion of parathormone.
The conditions are
Muscle spasm known as Tetany (sustained contraction of muscles in face, larynx, hands and feet).
Painful cramps of the limb muscles
Human insulin was first discovered by
Fredrick Banting, Charles Best and MacLeod in 1921.
Insulin was first used in treatment of diabetes on .
11th January 1922
The Islets of Langerhans consists of two types of cells namely alpha cells and beta cells.
The alpha cells secrete glucagon and beta cells secrete insulin.
A balance between insulin and glucagon production is necessary to maintain
blood glucose concentration.
Insulin
Insulin helps in the conversion of glucose into glycogen which is stored in liver and skeletal muscles.
It promotes the transport of glucose into the cells.
It decreases the concentration of glucose in blood.
Glucagon
Glucagon helps in the breakdown of glycogen to glucose in the liver.
It increases blood glucose level
The deficiency of insulin causes
Diabetes mellitus
: Increase in blood (Hyperglycemia). sugar level
: Excretion of excess glucose in the urine (Glycosuria).
: Frequent urination (Polyuria).
: Increased thirst (Polydipsia).
: Increase in appetite (Polyphagia).
The adrenal glands are located above each kidney. They are also called
supra renal glands.
The outer part is the adrenal cortex and the inner part is the adrenal medulla. .
The two distinct parts are structurally and functionally different
The adrenal cortex consists of three layers of cells. They are
zona glomerulosa, zona fasciculata and zona reticularis
The hormones secreted by the adrenal cortex are corticosteroids. They are classified into
a. Glucocorticoids
b. Mineralocorticoids
Glucocorticoids
The glucocorticoids secreted by the zona fasciculata are _______ and ______
cortisol and corticosterone
* They regulate cell metabolism.
* It stimulates the formation of glucose from glycogen in the liver.,
*It is an anti-inflammatory and anti-allergic agent.
The mineralocorticoids secreted by zona glomerulosa is
aldosterone
It helps to reabsorb sodium ions from the renal tubules.
It causes increased excretion of potassium ions.
It regulates electrolyte balance, body fluid volume, osmotic pressure and blood pressure.
The cortisol hormones of adrenal cortex serves to maintain the body in living condition and recover it from the severe effects of stress reactions. Thus an increased output of cortisol is “life saving” in “shock conditions”. It is also known as .
life-saving hormone
The adrenal medulla is composed of ________. They are richly supplied with sympathetic and parasympathetic nerves.
chromaffin cells
Hormones of Adrenal Medulla
It secretes two hormones namely
a. Epinephrine (Adrenaline) : b. Norepinephrine (Noradrenaline)
They are together called as “Emergency hormones”. It is produced during conditions of stress and emotion. Hence it is also referred as “flight, fright and fight hormone”.
Functions of adrenal medullary hormones
Epinephrine (Adrenaline)
It promotes the conversion of glycogen to glucose in liver and muscles
It increases heart beat and blood pressure.
It increases the rate of respiration by dilation of bronchi and trachea.
It causes dilation of the pupil in eye.
It decreases blood flow through the skin.
Norepinephrine (Noradrenalin)
Most of its actions are similar to those of epinephrine.
Leydig cells form the endocrine part of the testes. They secrete the male sex hormone called .
testosterone
Functions of testosterone
It influences the process of spermatogenesis.
It stimulates protein synthesis and controls muscular growth.
It is responsible for the development of secondary sexual characters (distribution of hair on body and face, deep voice pattern, etc).
The ovaries are the female gonads located in the pelvic cavity of the abdomen. They secrete the female sex hormones
a. Estrogen
b. Progesterone
Estrogen is produced by the _____ of the ovary and progesterone from the _____ that is formed in the ovary from the ruptured follicle during ovulation.
Graafian follicles
corpus luteum
Functions of estrogens
It brings about the changes that occur during puberty.
It initiates the process of oogenesis.
It stimulates the maturation of ovarian follicles in the ovary.
It promotes the development of secondary sexual characters (breast development, high pitched voice etc).
Functions of progesterone
It is responsible for the premenstrual changes of the uterus.
It prepares the uterus for the implantation of the embryo.
It maintains pregnancy.
It is essential for the formation of placenta.
_______ is partly an endocrine gland and partly a lymphoid gland. It is located in the upper part of the chest covering the lower end of trachea
Thymus
______ is the hormone secreted by thymus.
Thymosin
Functions of Thymosin
It has a stimulatory effect on the immune function.
It stimulates the production and differentiation of lymphocytes.
Gibberellins cause:
a) Shortening of genetically tall plants
b Elongation of dwarf plants
c) Promotion of rooting
d) Yellowing of young leaves
Elongation of dwarf plants
The hormone which has positive effect on apical dominance is:
a) Cytokinin
c) Gibberellin
b) Auxin
d) Ethylene
Auxin
Which one of the following hormones is naturally not found in plants:
a) 2, 4-D
b) GA3
c) Gibberellin
d) IAA
a) 2, 4-D
. Avena coleoptile test was conducted by
a) Darwin
b) N. Smit
c) Paal
d) F.W. Went
F.W. Went
To increase the sugar production in sugarcanes they are sprayed with
a) Auxin
b) Cytokinin
c) Gibberellins
d) Ethylene
Gibberellins
LH is secreted by
a) Adrenal gland
b) Thyroid gland
c) Anterior pituitary
d) Hypothalamus.
Anterior pituitary
Identify the exocrine gland
a) Pituitary gland
b) Adrenal gland
e) Salivary gland
d) Thyroid gland
Salivary gland
______causes cell elongation, apical dominance and prevents abscission
Auxins
_______ causes stomatal closure
abscisic acid (ABA)
The hormone which has negative effect on apical dominance is
Cytokinin
