Class 10 Science Chapter 6
Control and Coordination
Important Questions

Ans: The “Control and Coordination” chapter in Grade 10 CBSE Science explores the mechanisms through which living organisms regulate and synchronize their functions. It delves into topics such as the nervous system, coordination in plants, and the role of hormones in animals, shedding light on how organisms maintain balance and respond to their surroundings.

Ans: At the synapse, (functional junction between neurons) axon terminal comes in close proximity to the dendron terminal of the next neuron. Axon terminal is expanded to form a pre-synaptic knob and the other dendrite terminal forms post- synaptic depression.In between the two, lies a narrow fluid filled space called synaptic cleft. As the nerve impulse reaches the presynaptic knob, the synaptic vesicles get stimulated to release neurotransmitters in the synaptic cleft. The neurotransmitter molecules diffuse across the gap to come in contact with the postsynaptic membrane. In this way, nerve impulse passes across the minute gap to stimulate the dendron of other neurons. The synapse acts as a one-way valve to conduct impulse in one direction only. This is so because a chemical substance called neurotransmitter is secreted only on one side of the gap, i.e., on the axon’s side. It carries impulse across the synapse and passes it to the dendron of the other neuron. In this way, impulses travel across the neurons only in one direction, i.e., from the axon of one neuron to the dendron of another neuron through a synapse.

Ans: Reflex action is an automatic and spontaneous response to a stimulus. The pathway taken by nerve impulses and responses in a reflex action is called a reflex arc. It consists of the receptor, sensory nerve (afferent), spinal cord, motor nerve (efferent) and effector (muscles or glands). Reflex arc is evolved in animals because the thinking process of the brain is not fast enough. Reflex arc enables the body to give quick responses to harmful stimuli so that chances of damage to the body are decreased. It also prevents overloading of the brain, so it prevents fatigue. Many animals have very little or none of the complex neuron network needed for thinking. So, it is likely that the reflex arc has evolved as an efficient way of functioning in the absence of true thought processes. However, even after complex neuron networks have come into existence, reflex arcs continue to be more efficient for quick responses.

Ans: Growth of pollen tube towards the ovule due to chemical stimulus during the process of fertilisation in a flower is an example of chemotropism.