CBSE Class 10 Science Chapter 7: Control and Coordination NCERT Solutions

Solution: The correct option is Cytokinin. Cytokinin is a type of plant hormone that plays a crucial role in cell division, growth, and differentiation in plants. Insulin is involved in regulating blood sugar in animals, Thyroxin is a hormone produced by the thyroid gland in animals, and Oestrogen is a primary female sex hormone in animals.

Solution: The gap between two neurons is called a synapse. A synapse is the junction where information is transmitted from one neuron (nerve cell) to another. Dendrites and axons are parts of a single neuron, and an impulse is the electrical signal transmitted along a neuron.

Solution: The brain is responsible for all of the above. It is the central organ of the nervous system, controlling thought processes, memory, emotions, and consciousness. It also regulates vital involuntary functions like heartbeat and respiration, and maintains body posture and balance.

Solution: Receptors are specialized sensory cells or organs located throughout the body that detect specific stimuli from the environment. Their primary function is to sense external stimuli such as heat, cold, pain, pressure, light, and sound, and convert these stimuli into electrical signals (nerve impulses).

These nerve impulses are then transmitted via sensory neurons to the central nervous system (brain and spinal cord) for processing and response.

Situations where receptors do not work properly and likely problems:

• Damaged Receptors: If receptors are damaged, they may not be able to detect stimuli accurately or at all. For example, if pain receptors in the skin are damaged, a person might not feel a sharp object or extreme heat, leading to unnoticed injuries like cuts or burns. Similarly, if photoreceptors in the eyes are damaged, vision can be impaired, leading to blindness or partial sight loss.
• Loss of Sensitivity: Sometimes receptors can become less sensitive. For instance, prolonged exposure to a strong smell might lead to the olfactory receptors becoming less responsive, making it difficult to detect the smell after some time.
• Incorrect Signals: In some conditions, receptors might send incorrect signals. For example, certain neurological disorders can cause abnormal sensations like tingling or numbness, even without an external stimulus.

In summary, malfunctioning receptors can lead to a loss of sensory perception, delayed responses to danger, and potential physical harm due to the inability to detect harmful stimuli.

Solution: Neurons, also known as nerve cells, are the fundamental units of the nervous system responsible for transmitting information throughout the body. They are specialized cells that process and transmit chemical and electrical signals.

Structure of a Neuron: A typical neuron consists of three main parts:

1. Cell Body (Soma): This part contains the nucleus and other essential organelles. It is the metabolic center of the neuron.

   

2. Dendrites: These are branched, tree-like extensions that receive signals (nerve impulses) from other neurons or sensory receptors and transmit them towards the cell body.
3. Axon: This is a long, slender projection that carries nerve impulses away from the cell body towards other neurons, muscles, or glands. The axon typically ends in nerve endings (axon terminals), which release neurotransmitters to communicate with the next cell.

Function of a Neuron: The primary function of a neuron is communication. Neurons receive stimuli, process them, and transmit signals rapidly over long distances. This transmission occurs in two forms:

• Electrical Transmission: Within a neuron, the signal travels as an electrical impulse (action potential) along the axon.
• Chemical Transmission: At the synapse (the gap between neurons), the electrical signal is converted into a chemical signal. The nerve ending releases neurotransmitters, which diffuse across the synapse and bind to receptors on the next neuron, triggering a new electrical impulse or inhibiting it.

Through this process, neurons form complex networks that enable the nervous system to control and coordinate all bodily activities, including movement, sensation, thought, and emotion.