‘LH or ICSH control the secretion of hormones of reproductive glands of human body’ – judge the validity of the statement?

The luteinizing hormone (LH) is a hormone that permits regulating the female reproductive system. It stimulates the ovaries to release eggs and causes the uterus to prepare for pregnancy. ICSH is a hormone produced by the anterior lobe of the pituitary gland that, in the male, stimulates the interstitial cells of the testes to produce testosterone; chemically identical to luteinizing hormone of the female. As the LH and ICSH stimulate the Leydig cells in males to secrete testosterone and in females the corpus luteum to secrete progesterone. This valid the statement.

Analyse the role of synthetic plant hormone in increasing the production and solving the problem of weed in agriculture.

Synthetic plant hormones are man-made compounds that mimic naturally occurring chemical messengers found in plants. They may be used to accelerate some characteristic of a plant's growth and development which can be useful for farmers striving to improve yields. An example of a synthetic plant hormone is Indole-3-butyric acid (IBA) which mimics Indole-3-acetic acid (IAA) and acts as a growth hormone. Synthetic Hormone Roles Indole Acetic Acid (IAA) Apical dominance, Root growth Herbicides (e.g., 2,4-D) Killing of weeds Ethylene Ripening of the fruit

Distinguish between the functions of hormone and nervous system on the following parameters: Nature of function Pace of function Time spans of function Fate

Feature Function of hormone Nervous system Nature of function There are special chemicals which act as hormones and provide chemical coordination, integration and regulation in the human body. These hormones regulate metabolism, growth and development of our organs, the endocrine glands or certain cells. The neural system provides a point-to-point rapid coordination among organs. Pace of function Can be slow The nervous system allows an organism to respond quickly to changes in the internal or external environment. Feature or Characteristic Functions of hormone Nervous System Time span of function Long-lasting Short-lived Fate The hormones bind to the target receptor that activates the enzymatic activity of the cell to bring about biochemical changes. They are excreted from human body after producing desired effects. Once they have been released and have bound to postsynaptic receptors, neurotransmitter molecules are immediately deactivated by enzymes in the synaptic cleft; they are also taken up by receptors in the pre-synaptic membrane and recycled.

What influences gibberellin hormone exert on the seeds and internode of plants. Explain.

Plant growth regulators are chemical substances that affect the growth and differentiation of plant cells. They are chemical messengers that facilitate intracellular communication. These are also known as plant hormones. Gibberellins or Gibberellic acids are non-nitrogenous organic acids having a terpenoid group functioning as growth-promoting substances. A group of plant growth hormones obtained from the extract of the fungus Gibberella fujikuroi is known as Gibberellins. They promote stem elongation and differentiation in the presence of auxins. Gibberellins are the plant hormones, they stimulate cell division and elongation, break seed dormancy, and seed germination. The seeds of some species are hard to germinate; you can soak them in a GA solution to get them started.

Draw a neat diagram of the vertical section of the eyeball of human eye and label the following parts: (a) Choroid (b) Optic nerve (c) Iris (d) Yellow spot

The adult human eyeball is spherical shaped. The wall of the eyeball is composed of three layers- sclera, choroid and retina. Choroid is the middle layer, bluish in colour and contains many blood vessels. Its posterior two third region is thin while anterior region is thick to form ciliary body. Pigmented and opaque part of ciliary body is known as iris. Retina is the inner layer and consists of three sub layers- ganglional cells, bipolar cells and photoreceptor cells. The innermost ganglionic cells give rise to optic nerve fibre that forms optic nerve in each eye and is connected with the brain. Optic nerves leave the eye from the median posterior poll of the eyeball. Photoreceptors are absent in this region and hence is called the blind spot. A yellow spot on the eye is an abnormal growth usually found on the sclera near the cornea.

Write the two adaptive significance of air sacs for pigeons.

Air sacs, the air-filled extension of the breathing apparatus of the mammals are found connected to the lungs of the pigeons. It is seen that the lungs of the pigeon get fresh air during the process of both exhalation and inhalation, as the air sacs act all the pumping and the lungs only absorb oxygen. These air sacs perform to boost respiratory efficiency by providing a large surface area for gas exchange.