Class 10 Science Chapter 6 MCQ

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.

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

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.

Pituitary gland is present just below the brain. The gland secretes a number of hormones. One of the hormone secreted by pituitary gland is growth hormone. The growth hormone controls the growth of the human body.

Testes are paired glands present in males, secretes male sex hormone (testosterone) which control the development of male sex organs and male features as deep voice etc. i.e. changes associated with puberty. Ovaries are paired glands present in females, secretes female sex hormone (oestrogen and progesterone). Oestrogen which control the development of female sex organs and female features as soft skin etc. And progesterone controls uterus changes during menstrual cycle and helps in maintenance of pregnancy.

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

Iodine is necessary for the synthesis of thyroxine hormone, deficiency of it in the diet of a person produces less thyroxine hormone and causes a disease known as goitre. The main symptom of goitre is that the neck of the person appears to be swollen (due to the enlargement of thyroid gland situated in the neck).

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

The nervous system is made up of the longest special cell called neurons.

The information acquired at the end of the dendritic tip of a neuron causes a chemical reaction that produces an electrical impulse. This impulse travels from dendrite to cell body and then along axon to its end.

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.

There are mainly two types of nerves in our body, “Cranial nerve” and “Spinal nerves”. The “Cranial nerves” connect all the parts in the head directly to brain. The “Spinal nerves” connect all the remaining parts of the body like muscles and skin to the spinal cord. But there is a also third type of nerves, called visceral nerves. Most of the visceral nerves connect the internal organs of the body to spinal cord though some also connect to “Brain”.

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.

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].

Iodine is necessary for the synthesis of thyroxine hormone, deficiency of it in the diet of a person produces less thyroxine hormone and causes a disease known as “goitre”. The main symptom of goitre is that the neck of the person appears to be swollen (due to the enlargement of thyroid gland situated in the neck).

A growth movement of a plant part in response to an external stimulus, towards or away from it is called tropism. Common stimuli in environment are given. Such as: Light is the type of phototropism, gravity is the type of geotropism, touch is the type of thigmotropism, chemical is a type of chemotropism, and water is a type of hydrotropism.

A receptor is a cell (or a group of cells) in a sense organ which is sensitive to a particular type of stimulus such as light, sound, etc. The common type of receptors are: i) Photoreceptors which are present in eyes detect light. ii) Gustatory receptors which are present in tongue detect taste. Iii) Olfactory receptors which are present in nose detect smell. iv) Thermo receptors which are present in skin detect heat or cold.

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.