Science M.C.Q

(A) tongue

Photo means light and tropism means movement. The bending of plant shoots in response to light is called phototropism.

Spinal cord begins in continuation with medulla and extends downwards.

Insulin is produced in the pancreas. It regulates blood sugar level and its deficiency causes diabetes. The growth and development of the body is regulated by the growth hormone.

Pituitary gland is unpaired gland.

Deficiency of insulin causes diabetes.

Testosterone is the male sex hormone which is associated with male puberty.

Hormones of thyroid gland have iodine as their structural component.

The growth of pollen tubes towards the ovule caused by a sugary substance is an example of chemotropism.

Phototropism is the growth of a plant in the direction of light. It is one of the many plant tropisms or movements which respond to external stimuli.
Thus, the movement of the sunflower towards the sun is due to phototropism.

Abscisic acid serves to form of layer of abscission.

The stimulus in thigmotropism is touch which causes movement.

The pituitary gland secretes a hormone known as growth hormone which controls the growth of the human body.
Deficiency of growth hormone can make the person very short, while excess of this hormone can make a person very tall.

Phototropism is the response of the plants towards light. Thus, sunflower moves in accordance with the path of sun.

Roots do not respond to touch.

Roots bend away from the light source and show negative phototropism.

Cerebellum controls posture and balance of the body.

The hindbrain consists of three centres called the pons, the cerebellum and the medulla.
The forebrain consists mainly of the cerebrum.
The midbrain does not have any further divisions.
The spinal cord is a cylindrical structure.

The olfactory receptors which detect smell are located in the nose.

In a synapse, a chemical signal is transmitted from the axon end of one neuron to the dendrite end of the adjacent neuron.

The contraction of the pupil of the eye in the presence of a bright light is an example of cerebral reflex. A reflex action that involves the brain is called cerebral reflex. It is found in the organs present in the head that are directly connected to the brain.

Hormones can be grouped into three main types : amines, these are simple molecules. proteins and peptides which are made from chains of amino acids. steroids which are derived from cholesterol.

The growth of tendrils in pea plants is due to the rapid cell division and elongation in tendril cells in contact with the support.

Adrenaline is secreted by the adrenal glands which are located on top of the kidneys.

Synapse is the junction between two neurons.

This is an example of thigmotropism.

The primary function of the auxin hormones is to elongate plant cells in the stem. For instance, auxins are the hormones responsible for phototropism, the growth of a plant toward the light.

All of the above are gastrointestinal hormones,

The hypothalamus is the processing centre in the brain that controls body temperature. It does this by triggering changes to effectors, such as sweat glands and muscles controlling body hair.

Chewing is a voluntary action, while actions like vomiting, heart beat and salivation are involuntary.

The rolling up of plant leaves on touching is a thigmonastic movement and it is not related to growth.

A synapse is a functional junction between the axon of a neuron and the dendrites of the next neuron. It is separated by a small gap known as the synaptic cleft.