Summary of the Chapter-6-Control and Coordination with Key-Points:
- The nervous system and hormones are responsible for control and coordination within our bodies.
- The nervous system's responses are categorized as reflex actions, voluntary actions, or involuntary actions.
- Electrical impulses are the means by which the nervous system sends messages.
- The nervous system gathers information from sensory organs and elicits responses through muscles.
- Both plants and animals exhibit chemical coordination.
- Hormones are released in one area of an organism and travel to different locations to produce the intended effect.
- Hormonal actions are regulated by a feedback mechanism.
1. What is the primary role of nervous tissue in animals?
(A) Controlling and coordinating electrical impulses from the environment
(B) Detecting chemicals in the environment
(C) Facilitating blood circulation
(D) Regulating hormone production
Explanation: Nervous tissue is specialized for conducting electrical impulses from one part of the body to another, allowing animals to respond to changes in their environment efficiently.
2. Which part of the brain is responsible for maintaining posture and balance?
(A) Fore-brain
(B) Mid-brain
(C) Cerebellum
(D) Medulla
Explanation: The cerebellum is located in the hind-brain and is responsible for the precision of voluntary actions and maintaining the posture and balance of the body.
3. What is a reflex action?
(A) A voluntary response to environmental stimuli
(B) A quick, involuntary response to stimuli
(C) An action that involves thinking before responding
(D) A slow, conscious reaction to an event
Explanation: Reflex actions are quick and involuntary responses to stimuli that do not involve the conscious parts of the brain, making them automatic and fast.
4. In a neuron, where is the electrical impulse converted into a chemical signal?
(A) At the cell body
(B) At the synapse
(C) In the dendrites
(D) In the axon
Explanation: The electrical impulse in a neuron is converted into a chemical signal at the synapse to allow transmission to the next neuron or muscle cell.
5. What is the function of the medulla in the human brain?
(A) Controls voluntary movements
(B) Regulates involuntary actions like heartbeat and breathing
(C) Facilitates memory and learning
(D) Coordinates balance and posture
Explanation: The medulla, located in the hind-brain, controls involuntary functions such as heart rate, blood pressure, and respiration.
6. What term describes the directional growth of a plant in response to gravity?
(A) Phototropism
(B) Geotropism
(C) Hydrotropism
(D) Chemotropism
Explanation: Geotropism is the movement or growth of a plant in response to gravity. Roots grow downward (positive geotropism), while shoots grow upward (negative geotropism).
7. What role do plant hormones play?
(A) They help in conducting electrical impulses.
(B) They control and coordinate growth, development, and environmental responses.
(C) They facilitate digestion.
(D) They are involved in respiration.
Explanation: Plant hormones regulate growth, development, and responses to environmental stimuli. For example, auxins promote growth by cell elongation.
8. Which hormone is responsible for regulating blood sugar levels in the human body?
(A) Adrenaline
(B) Thyroxin
(C) Insulin
(D) Growth hormone
Explanation: Insulin, secreted by the pancreas, regulates the sugar levels in the blood. A deficiency or lack of insulin causes elevated blood sugar levels, leading to diabetes.
9. What triggers the secretion of adrenaline in animals?
(A) Hunger
(B) Fear or stress
(C) Sleep
(D) Digestion
Explanation: Adrenaline is secreted in response to stress or fear, preparing the body for a "fight or flight" response by increasing heart rate, breathing rate, and directing blood flow to muscles.
10. Which part of the neuron first receives the stimulus from the environment?
(A) Axon
(B) Synapse
(C) Dendrite
(D) Cell body
Explanation: The dendrites are specialized structures on a neuron that first receive the stimulus from the environment and initiate the electrical impulse transmission.
11. Which of the following statements about reflex arcs is true?
(A) Reflex arcs are formed in the brain.
(B) Reflex arcs are designed for quick responses without involving the brain.
(C) Reflex arcs involve the brain for thinking and decision-making.
(D) Reflex arcs are responsible for slow, voluntary actions.
Explanation: Reflex arcs are formed in the spinal cord to allow for fast responses to stimuli without involving the brain. This helps to protect the body from harm in situations where quick reactions are needed, like touching a hot object.
12. What is the function of synapses in the nervous system?
(A) They speed up nerve impulses.
(B) They allow electrical impulses to travel continuously.
(C) They enable the transmission of chemical signals between neurons.
(D) They store information in the brain.
Explanation: Synapses are junctions between neurons where the electrical impulse is converted into a chemical signal to transmit the message to the next neuron or target cell.
13. Which plant hormone is responsible for promoting cell division?
(A) Auxin
(B) Gibberellin
(C) Cytokinin
(D) Abscisic acid
Explanation: Cytokinins promote cell division and are found in high concentrations in areas of rapid growth, such as fruits and seeds.
14. What is the role of adrenaline in the "fight or flight" response?
(A) Reduces heart rate and blood flow to muscles
(B) Increases blood flow to the digestive system
(C) Increases heart rate, breathing, and redirects blood to muscles
(D) Slows down breathing and digestion
Explanation: Adrenaline prepares the body for emergency situations by increasing heart rate, breathing, and redirecting blood flow to the muscles to prepare for quick action, either fighting or fleeing.
15. Which part of the nervous system is responsible for reflex actions?
(A) Brain
(B) Spinal cord
(C) Heart
(D) Peripheral nerves
Explanation: Reflex actions are coordinated by the spinal cord. The spinal cord acts as the main relay center for reflexes, allowing for quick responses without involving the brain.
16. What happens at the neuromuscular junction?
(A) The brain sends direct signals to muscles.
(B) Electrical impulses from neurons are converted into mechanical responses in muscles.
(C) Muscles produce their own electrical impulses.
(D) Chemical signals are transferred from muscles to neurons.
Explanation: At the neuromuscular junction, the electrical signal from a neuron is converted into a chemical signal, which then triggers a mechanical response in the muscle, leading to movement.
17. Which hormone is involved in regulating the menstrual cycle in females?
(A) Testosterone
(B) Insulin
(C) Estrogen
(D) Growth hormone
Explanation: Estrogen, produced by the ovaries, is responsible for the development of female secondary sexual characteristics and regulating the menstrual cycle.
18. What type of movement in plants is due to growth in response to environmental stimuli?
(A) Reflex action
(B) Tropic movement
(C) Nastic movement
(D) Photochemical reaction
Explanation: Tropic movement is a type of plant movement in response to environmental stimuli like light (phototropism), gravity (geotropism), or water (hydrotropism), and it involves growth.
19. How does auxin help a plant to grow towards light?
(A) It stimulates cell division in the shoot.
(B) It causes cells on the shaded side to grow longer, bending the shoot toward the light.
(C) It makes the roots grow faster.
(D) It causes cells on the side of the plant facing the light to grow longer.
Explanation: Auxin is a plant hormone that accumulates on the shaded side of the plant, causing those cells to elongate more than the cells on the light side, resulting in the shoot bending towards the light.
20. Which part of the brain is known as the main thinking part?
(A) Mid-brain
(B) Hind-brain
(C) Fore-brain
(D) Spinal cord
Explanation: The fore-brain is responsible for higher cognitive functions, such as thinking, memory, decision-making, and voluntary actions. It includes regions for sensory processing and motor control.