Class 10 Science Chapter 6 MCQ

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

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

Hormones are a kind of chemical messengers. A hormone is produced in one part of the body but it acts on some other part of the body. The hormones are of different types and perform different functions as per need in the body.

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.

The person having high sugar level in blood is called a “Diabetic”. Such persons are advised to take less sugar in diet, reduce weight, exercise regularly. Persons with severe diabetes (high sugar level in blood) are treated by giving injections of insulin. Pancreas secrete the hormone insulin. Its function is to regulate blood sugar level. Deficiency of insulin causes a disease known as diabetes that is characterized by large quantities of sugar in blood and even urine. Growth hormone secreted by the pituitary gland regulates growth and development of the body.

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

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

The brain is broadly divided into three regions: forebrain, midbrain and hindbrain. The forebrain consists mainly of cerebrum. The midbrain does not have any further division. The hindbrain consists of 3 centres called, pons, cerebrum and medulla.

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.

Abscisic acid is responsible for the formation of layer of abscission. This layer disconnects the living tissue of leaf from the other parts.

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 growth of a pollen tube towards ovule is in induced by a chemical (sugar) substance secreted by the ripened stigma of flower into the style towards ovary. It is an example of chemotropism, pollen grain response to a stimulus by growing a pollen tube in downward direction, towards ovule for fertilization.

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.

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.

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.