1.What is a stimulus? Give three examples of external stimuli that animals respond to, and explain why response is vital for survival.
2.Draw a neat, labelled diagram of a neuron (nerve cell). Label the dendrite, cell body (cyton), axon, and nerve endings. Explain the direction of nerve impulse flow.
3.What is a synapse? Explain how electrical impulses are converted into chemical signals at a synapse to cross the gap between two neurons.
4.Differentiate between sensory neurons, motor neurons, and relay (association) neurons in terms of their location and function.
5.What are receptors? Name the five key receptors present in our sense organs and specify the stimulus each receptor detects.
6.Define reflex action. Why is a reflex action called an involuntary, spontaneous response? Explain with two daily-life examples.
7.What is a reflex arc? Draw a neat flowchart or block diagram showing the path of a nerve impulse during a reflex action starting from the receptor to the effector.
8.Why have reflex arcs evolved in animals, when the thinking process of the brain is already present? Explain the evolutionary advantage.
9.Describe the neuromuscular junction. Explain how the electrical impulse in a motor neuron is translated into muscle contraction (movement).
10.How does the nervous tissue cause action? Explain in detail the role of specialized muscle proteins and changes in shape of muscle cells.
11.What are the three major parts of the human brain? List their sub-divisions and describe their functions.
12.What is the role of the cerebellum in our body? Explain how it helps in maintaining posture, balance, and precision of voluntary movements (like riding a bicycle).
13.Name the part of the hindbrain that controls involuntary actions like salivation, vomiting, and blood pressure. State how this part is structured.
14.How are the brain and the spinal cord protected from mechanical shocks and injuries? Discuss the role of cranium, vertebral column, and cerebrospinal fluid (CSF).
15.Differentiate between voluntary actions, involuntary actions, and reflex actions, giving one suitable example of each.
16.Why do plants lack a nervous system and muscular tissue, yet are capable of coordinating their responses? Explain.
17.Differentiate between nastic movements (non-directional) and tropic movements (directional) in plants, giving one example of each.
18.Describe the movement of leaves in the "touch-me-not" plant (Mimosa pudica) when touched. Explain the electrical-chemical means and water loss (turgor changes) involved.
19.Define phototropism. Explain with a neat description or experiment how shoots show positive phototropism and roots show negative phototropism.
20.Explain the mechanism of geotropism. How do roots and shoots respond to gravity? Describe an experiment with a potted plant placed horizontally.
21.Define chemotropism. Give a classic example of chemotropism in plants that occurs during the fertilization process.
22.What is hydrotropism? Describe a simple laboratory experiment to demonstrate positive hydrotropism in germinating pea seeds.
23.How does a climbing tendril of a pea plant circle and cling to a support? Explain in terms of hormone concentration on the side in contact vs the free side.
24.Why are plant movements in response to stimuli generally slower than animal movements? Discuss in terms of growth vs muscular contraction.
25.How do plant cells communicate information about external stimuli to other parts of the plant body, given the absence of synapses?
In a practical class, a student accidentally touches a hot glass beaker. Immediately, without thinking, his hand pulls away. The teacher explains that this is a reflex action designed to prevent tissue damage, mediated by a pathway in the spinal cord before the signal reaches the brain.
41.Based on Case Study 1, answer the following:
- Identify the receptor, effector, and the organ acting as the coordinator in this reflex action.
- Trace the pathway of the electrical impulse from the skin to the muscle using a simple text flow scheme.
- If the spinal cord of a person is injured, which signals will be disrupted, and will the person still show this reflex action?
Anika grows a plant inside a closed cardboard box with a single small opening on the left side that allows sunlight to enter. After 5 days, she observes that the stem of the seedling has bent significantly towards the left opening, while the roots have grown away from it.
42.Based on Case Study 2, answer the following:
- Identify the plant hormone responsible for this directional bending. Where is it synthesized?
- Explain the exact cellular mechanism that causes the stem to bend towards the light source. (Mention shaded vs lit sides).
- What is the biological significance or survival advantage of this phototropic response for shoots?
In a rural health camp, a doctor diagnoses several villagers with swollen necks, a condition called goitre. He learns that the local soil and water are highly deficient in iodine, and the villagers use non-iodized sea salt for cooking. He initiates a campaign to distribute iodized salt.
43.Based on Case Study 3, answer the following:
- Why is iodine necessary for our body? Which gland requires iodine, and what hormone does it produce?
- Explain the metabolic consequences of thyroxine deficiency. Why does this deficiency cause goitre?
- Why did the doctor recommend iodized salt instead of pure chemical iodine? Explain in terms of daily nutrition.
Mr. Verma has severe Type-1 diabetes. Every day, before eating his meals, he measures his blood glucose level and self-injects a calculated dose of insulin hormone. One day, he forgot to take his injection, and within hours, his blood glucose levels shot up to dangerous levels, causing extreme fatigue.
44.Based on Case Study 4, answer the following:
- What is the biological function of insulin? Which cells in the pancreas secrete it?
- Why cannot insulin be taken orally as a pill instead of an injection? Explain based on protein digestion.
- Explain how Mr. Verma's body would normally regulate glucose levels using a feedback loop if he were healthy.
A biology teacher places a healthy potted tomato plant horizontally on its side in a dark room. After 48 hours, she shows the class that the shoot tip has curved and grown upwards (defying gravity), while the root tips have curved downwards towards the soil.
45.Based on Case Study 5, answer the following:
- Name the biological phenomenon demonstrated by the shoots and the roots in this experiment.
- Explain why shoots bend upwards while roots bend downwards when placed horizontally. Discuss the differential effect of auxin on root vs shoot cell elongation.
- Why was the experiment performed in a dark room? Explain the experimental control.
While walking in a forest, Rohan suddenly comes face-to-face with a wild bear. Immediately, Rohan's heart starts beating rapidly, his breathing quickens, his skin becomes pale, and he feels a sudden surge of energy that helps him climb a nearby tree quickly to safety.
46.Based on the Fight-or-Flight Encounter, answer the following:
- Identify the emergency hormone released in Rohan's body. Which gland secreted it?
- Explain the biological rationale behind: (a) rapid heartbeat, (b) quick breathing, and (c) pale skin (reduced blood flow to skin).
- How does the release of this hormone help in sudden, intense physical action? Explain.
A gland 'A' located on top of the kidneys secretes hormone 'X' which controls heart rate and blood pressure in stress. Another gland 'B' located in the neck secretes hormone 'Y' which regulates carbohydrate, protein, and fat metabolism. A master gland 'C' located at the base of the brain controls both 'A' and 'B'.
47.Based on the puzzle description, answer the following:
- Identify glands 'A', 'B', 'C', and hormones 'X', 'Y'.
- Explain the relationship between master gland 'C' and the thyroid gland. How does 'C' regulate thyroid activity?
- What would happen to a child if master gland 'C' under-secretes growth hormone during early childhood?
48.Draw a schematic diagram of a synapse. Label the axon terminal, synaptic vesicles, neurotransmitters, synaptic cleft, and dendrite membrane. Explain the role of calcium ions in neurotransmitter release.
49.What is the difference between a nerve and a tract? Explain the composition of a peripheral nerve.
50.Describe the path of light reflex (pupil constriction in bright light). Trace the sensory and motor path through the midbrain.
51.Why is the spinal cord considered the primary center for reflex actions? Discuss its structure (white matter and grey matter arrangement).
52.What are the characteristics of a chemical signal compared to an electrical signal? State two limitations of electrical signals in nervous coordination.
53.Explain how abscisic acid helps plants survive extreme drought conditions. (Stomatal closure mechanism).
54.Explain photoperiodism in plants. How do plants coordinate their flowering times in response to seasonal changes in day length?
55.Differentiate between exocrine glands and endocrine glands based on: (a) presence of ducts, (b) secretion products, and (c) mode of transport of secretion.
56.What is the hypothalamus? Explain its role in acting as the crucial link between the nervous system and the endocrine system.
57.Describe the location and secretion of the parathyroid glands. State the function of parathormone and the effects of its deficiency.
58.Explain how the ovaries and testes act as dual-function organs (cytogenic and endocrine functions). Name the hormones they secrete.
59.What is dwarfism and gigantism? Explain their endocrine causes.
60.Why is goitre highly common in mountainous regions like the Himalayas? Explain based on geochemical factors.
61.Describe the role of progesterone in the female reproductive cycle. Which temporary endocrine structure secretes it?
62.How do local tissue hormones (like prostaglandins) differ from classic circulating hormones?
63.What is the function of the hormone calcitonin? How does it coordinate with parathormone to maintain calcium homeostasis?
64.Explain why patients with severe diabetes suffer from frequent urination (polyuria) and extreme thirst (polydipsia) based on blood sugar levels and kidney function.
65.Explain the mechanism of action of non-steroid hormones (like insulin) via secondary messengers on the target cell membrane, compared to steroid hormones that enter the cell.
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