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].

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, one on top of each kidney that make adrenaline hormone. Testes are paired glands present in males, secretes male sex hormone. Pituitary grand is present just below the brain and is unpaired. It is also called master gland as it secretes a number of hormones. Ovaries are paired glands present in females, secretes female sex hormones.

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.

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

During cold, mucus in nasal passage becomes too thick, so that order molecules can’t reach the olfactory receptor cells. Thus, brain receives no signal identifying the odour, and so the smell of a perfume cannot be differentiating from that of an “Agarbatti”.

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”.

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.

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

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.

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.

Spinal cord is a cylindrical structure enclosed in a bony cage called vertebral column. It begins in continuation with medulla and extends downwards.

Cerebellum controls the voluntary action e.g. posture. The cerebrum (part of forebrain) is the main thinking part of the brain. It coordinates the voluntary action 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 respirations), cerebellum (helps in maintaining posture and balance the body) and medulla that controls involuntary actions such as breathing etc. The midbrain controls reflex movements.

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

The statement is false as sensory neuron carry signals from receptors to spinal cord. The statement is false as motor neurons carry signals from spinal cord to effectors. The pathway taken by nerve impulse in a reflex action is called the reflex arc. A reflex action is involuntary action in response to a stimulus e.g. coughing, sneezing, etc. It follows a specific pathway as given below: Stimulus → Receptors → Spinal cord → Effector → Response