Chapter 6. Control and Coordination

Class 10 Science Chapter 6. Control and Coordination CBSE Previous Questions and Answers :

Question : What is synapse ? How nerve impulse passes across synapse ? [SEBA 2015]

Answer :  A synapse is a junction between two nerve cells, where electrical or chemical signals are transmitted. When an electrical impulse reaches the presynaptic neuron, it triggers the release of neurotransmitters, which diffuse across the synaptic gap and bind to receptors on the postsynaptic neuron, generating a new electrical signal.

Question :  How Mimosa plant responses to stimulus ? [SEBA15] 

Answer : The Mimosa plant responds to stimuli by rapidly closing its leaves when touched or disturbed. Movement occurs at a point different from the touch due to electrical-chemical communication between cells. Cells change shape by altering water content, causing swelling or shrinking, resulting in consequent movement.

Question : How nervous tissue maintains muscular movement ? [SEBA16]

Answer :  Nervous tissue maintains muscular movement by transmitting electrical signals called action potentials along neurons. These signals travel from the central nervous system to motor neurons, which then stimulate muscle fibers to contract, allowing for coordinated movement.

Question : What is auxin ? How does it aid in the growth of a plant ? [SEBA 20]

Answer : Auxin is a plant hormone synthesized at the shoot tip.

In response to light, auxin diffuses to the shady side of the shoot. Its concentration there stimulates cell elongation, causing the cells on the shaded side to grow longer. This directional growth allows the plant to bend towards the light source, facilitating phototropism.

Question : How muscle cells change their shape ? [SEBA 20]

Answer : Muscle cells change shape in response to nervous electrical impulses. Special proteins within the cells alter both their shape and arrangement, leading to a shorter form when stimulated by these impulses.

Question : Write two difference between axon and dendrite . [SEBA 19]

Answer : The difference between axon and dendrite are :

Characteristic	Axon	Dendrite
Structure	Long, single extension	Short, branched extensions
Function	Transmits signals away from cell	Receives signals and transmits them towards the cell body

Question :  How does nerve impulse travel in our body ? [SBA18]

Answer :  Nerve impulses travel in our body by transmitting electrical signals along nerve cells. When a nerve impulse reaches a muscle, special proteins in muscle cells respond to the electrical signals, changing shape and arrangement, ultimately causing the muscle cells to shorten and produce movement.                                         

Question :  Write the function of Adrenaline hormone . [SEBA 17]

Answer : Adrenaline, secreted from the adrenal glands, regulates various physiological responses in the body. It targets organs like the heart, increasing heart rate for enhanced oxygen supply to muscles, while constricting blood vessels in the digestive system and skin to redirect blood flow to skeletal muscles. Adrenaline also stimulates increased breathing rates.

CBSE Class 10 Science Previous Questions and Answers :

Question:  Name two tissues that provide control and coordination in multi-cellular animals . [CBSE 2009 1M]

Answer : Nervous tissue and endocrine tissue provide control and coordination in multicellular animals. Nervous tissue coordinates rapid responses, while endocrine tissue regulates slower, systemic processes.

Question: How is the spinal cord protected in the human body ? [2010 1M]

Answer : The spinal cord is protected by the vertebral column, which is composed of individual vertebrae stacked on top of each other, forming a bony canal called the spinal canal.

Question: What are nastic and curvature movement ? Give one example of each . [2009 2M]

Answer : Nastic movements are reversible, non-directional plant responses to stimuli, such as changes in light or temperature. An example is the opening and closing of a flower in response to light. Curvature movements involve directional growth responses, like the bending of a plant toward or away from a stimulus, as seen in tropisms.

Question: What are hormones ? Name the hormone secreted by thyroid gland and state its function ? [2010 2M]

Answer : Hormones are chemical messengers produced by glands in the endocrine system, regulating various physiological functions in the body. The hormone secreted by the thyroid gland is thyroxine (T4). It plays a crucial role in regulating metabolism, growth, and development, as well as influencing heart rate, body temperature, and protein synthesis.

Question: (a) Name one gustatory receptor and one olfactory receptor present in human beings .

(b) Write a and b in the given flow chart of neuron through which information travels as an electrical impulse .

Dendrite   → a  → b  → Endpoint of Neuron        [2018 2M]

Answer : (a) One gustatory receptor in humans is the taste receptor for sweet, and one olfactory receptor is the receptor for the scent of roses.

(b)  In the given flow chart of a neuron, the pathway through which information travels as an electrical impulse is:

Dendrite → Cell Body (a) → Axon (b) → Endpoint of Neuron

Question: Name the hormones secreted by the following endocrine glands and specify one function of each :

(a) Thyroid  (b) Pituitary  (c) Pancreas   [2018 3M]

Answer :  (a) Thyroid gland secretes thyroxine (T4) and triiodothyronine (T3). Thyroid hormones regulate metabolism, growth, and development, and influence heart rate, body temperature, and protein synthesis.

(b) Pituitary gland secretes various hormones including growth hormone (GH). GH stimulates growth, cell reproduction, and regeneration in humans and other animals.

(c) Pancreas secretes insulin and glucagon. Insulin lowers blood glucose levels by promoting its uptake by cells, while glucagon raises blood glucose levels by stimulating the liver to release stored glucose.

Question:  What are plant hormones ? Name the plant hormones responsible for the following ?

(i) Growth of stem

(ii) Promotion of cell division

(iii) Inhibition of growth 

(iv) Elongation of cells [2019 3M]

Answer :  Plant hormones, also known as phytohormones, are chemical messengers that regulate various physiological processes in plants.

The plant hormones responsible for the mentioned functions are:

(i) Auxins - responsible for the growth of stems.

(ii) Cytokinins - promote cell division.

(iii) Abscisic Acid (ABA) - inhibits growth, particularly during stress conditions.

(iv) Gibberellins - responsible for the elongation of cells.

Question: A squirrel is in a scary situation . Its body has to prepare for either fighting or running away . State the immediate changes that take place in its body so that the squirrel is able to either fight or run . [2020 3M]

Answer : In response to the scary situation, the squirrel's body releases adrenaline, a hormone secreted from the adrenal glands. Adrenaline triggers widespread physiological changes, including increased heart rate, dilation of air passages for improved breathing, enhanced blood flow to muscles, and increased energy production, preparing the squirrel for either fighting or fleeing effectively.

Question: Why is chemical communication better than electrical impulses as a means of communication between cells in a multi-cellular organism ? [2020 3M]

Answer : Chemical communication is better than electrical impulses for intercellular communication in multicellular organisms because it can reach all cells in the body, whereas electrical impulses are limited to specific pathways. Chemical signals, such as hormones, travel through the bloodstream and can affect distant target cells. This enables coordinated responses and allows for more widespread and precise regulation of physiological processes.

Question: (a) Draw the structure of a neuron and label the following on it :

Nucleus , Dendrite , Cell body and Axon

(b) Name the part of neuron :

(i) Where information is acquired .

(ii) Through which information travels as an electrical impulse . [2008 5M]

Answer : (a)

(b) (i) Dendrites - where information is acquired by receiving signals from other neurons or sensory receptors.

(ii) Axon - through which information travels as an electrical impulse, transmitting signals away from the cell body toward other neurons or effector cells.

Question: (a) What is  (i) Phototropism  and  (ii) Geotropism ?

With labelled diagrams describe an activity to show that light and gravity change the direction that plant parts grow in .

(b) Mention the role of each of the following plant hormones :

(i) Auxin  (ii) Abscisic Acid   [2008 5M]

Answer : (i) Phototropism is the directional growth response of plants towards or away from light. Shoots exhibit positive phototropism by bending towards light, while roots display negative phototropism by bending away from it.

(ii) Geotropism is the directional growth response of plants in relation to gravity. Roots show positive geotropism, growing towards gravity, while shoots exhibit negative geotropism, growing away from it.

The provided activity demonstrates the effects of light and gravity on plant growth. Two to three freshly germinated bean seeds are placed on a wire mesh covering the neck of a conical flask filled with water. The flask is positioned in an open-sided cardboard box facing a window to allow light to enter. After a few days, shoots bend towards the light while roots grow away from it. The flask is then turned to position shoots away from light and roots towards it. After a few days, roots grow towards light, while shoots bend away from it. This experiment illustrates phototropism and gravitropism, showing how light and gravity influence plant growth directions.

(b) (i) Auxin promotes cell elongation and is involved in various aspects of plant growth and development, including phototropism (bending towards light) by stimulating cell growth on the shaded side of the plant.

(ii) Abscisic acid inhibits growth and mediates responses to environmental stressors, such as promoting leaf wilting during drought conditions.