Class 10 Science Chapter 6 MCQ

Here, all these statements are correct. Hence, your answer will be option [D].

In human beings, nervous system and endocrine system work together to control and coordinate all the activities. Both these systems consist of a number of organs that work together in a systematic way.

Junction between two neurons is called synapse. Cell Junction is a junction between neighboring cells. Neuromuscular Junction which connects nervous system to “Muscular System”.

Testosterone is the male sex hormone. It regulates male accessory sex organs. It is responsible for secondary sexual characters like moustache, beard, etc. thus, increasing fertility in males.

There are two adrenal glands in our body one on top of each kidney. The adrenal glands make adrenaline hormones when we are faced with any dangerous situation, then our nervous system stimulates the adrenal glands to secrete more adrenaline hormone into our blood, then we can react according to the situation.

Deficiency of growth hormone in childhood cause dwarfism while excessive secretion causes gigantism. Deficiency of thyroxine cause goitre. Adrenaline is secreted in small amounts all the time but is secreted in large amount to prepare our body for action during fight or flight.

Pituitary gland is known as “master gland” and adrenal glands are often called “glands of emergency”

Involuntary action are those actions that are not under our direct control such as heartbeat, breathing, Peristatic movement etc. These are controlled by medulla. Chewing is under voluntary control and controlled by lobes present in “Cerebral cortex”.

Medulla is part of hind brain. It controls the involuntary action and regulate reflex responses. The other parts of the hind brain are cerebellum and pons.

Here, all these statements are correct. Hence, your answer will be option [D].

Synapses actually act like one-way valves. This is because the chemical substance is present on only one side of the gap. Due to this, the nerve impulses or messages through a particular set of neurons can go across only from one side which contains the chemical substance. In this way, synapses ensure that nerve impulses travel in only one direction through a particular set of neurons.

The movement of a plant part in response to light is called phototropism.

The pathway or route taken by nerve impulse in a reflex action is called reflex arc. Reflex arcs allowed “Rapid response”.

Here, all these statements are correct. Hence, your answer will be option [D].

Here, all these statements are correct. Hence, your answer will be option [D].

Abscisic is a growth inhibitor hormone. It reverses the growth promoting effects of auxins and gibberellins. It causes dormancy of seeds, wilting of leaves, closing of stomata etc.

The main function of abscisic acid in plants is to inhibit growth. The other plant hormones with their functions are given. Such as: Auxins, promote cell elongation, root formation, cell division and other physiological process. Gibberellins, stimulate stem elongation, stem germination and flowering (opposite effect of ABA). Cytokinin, promotes cytokinesis also helps in breaking dormancy and regulating phloem transport. Abscisic acid, acts as growth inhibitor, causes dormancy of seeds, etc. promotes leaf and fruit fall, helps in stomata closing to prevent loss of H2O. Ethylene, promotes transverse growth, senescence, abscission of leaves etc.

Auxin hormone increases the rate of growth in a stem but it decreases the rate of growth in a root.

The cerebrum (part of forebrain) is the main thinking part of the brain. It coordinates the voluntary actions of the body. It has different areas for performing different functions such as centres of hearing, smell, memory, etc. The hindbrain consists of pons (takes part in regulating respiration), cerebellum (helps in maintaining posture and balance of body) and medulla that controls involuntary actions such as breathing etc. The midbrain controls reflex movements.

A microscopic gap between a pair of adjacent neurons over which nerve impulses pass when going from one neuron to the next is called synapse. The neurons carry messages in the form of electrical signals called “electrical impulses” or “nerve impulses”. The dendrites pick up the impulses from receptor and pass them to the cell body, and then along the axon to its end. At the axonal end, electrical impulses set off release of some chemicals that crosses the gap or synapse and start a similar impulse in dendrite of the next neuron.