(b) Electrical impulse is an excellent means to transmit information in the animal body, but there are some limitations to the use of electrical impulses. State any two limitations.
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(a) The timing and amount of hormone released are regulated by feedback mechanism. For example, if the sugar levels in the blood rise, they are detected by the cells of the pancreas which respond by producing more insulin. As the blood sugar level falls, insulin secretion is reduced. (Any other suitable example) (2 Marks) OR (b) * Electrical impulse reaches only those cells that are connected by nervous tissue, not each and every cell in the animal body. (1 Mark) * Once an electrical impulse is generated in the cell and transmitted, the cell will take some time to reset its mechanism before it can generate and transmit a new impulse. / Transmission of electrical impulses is not a continuous process. (1 Mark)
Attempt either subpart (a) or (b) : (a) Electrical impulses are an excellent means to respond to stimuli in animal bodies. List any two limitations to the use of electrical impulses.
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(a) (i) Electrical impulses will reach only those cells that are connected by nervous tissue, not each and every cell in the animal body. (1 Mark) (ii) Once an electrical impulse is generated in a cell and transmitted, the cell will take some time to reset its mechanisms before it can generate and transmit a new impulse / cell cannot continuously create and transmit electrical impulses. (1 Mark)
Give differences between the following : (a) Nephron and neuron (b) Sensory nerve and motor nerve (c) Consumers and decomposers
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(a) Nephron Neuron (i) Filtration/Structural/ (i) Structural/ Functional unit 1 Functional unit of the kidney. of the nervous system. (ii) Filters nitrogenous wastes (ii) Transmits information from the blood. from one part of the body to another. (any one, any other suitable difference) (b) Sensory Nerve Motor Nerve (i) Carries impulse from receptors (i) Carries impulse from 1 to CNS/ Brain and Spinal cord. CNS/Brain and Spinal cord to the motor area/ effector organ. (any other suitable difference) (c) Consumers Decomposers (i) Organisms that feed on (i) Organisms that breakdown producers and other dead organic matter into 1 consumers. simpler inorganic substances. (ii) Transfers energy through the (ii) Recycle nutrients back into food chain. the environment. (any one, any other suitable difference) 3
State two differences between the act of chewing food and salivation on sight of food.
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Chewing of food i) It is a voluntary action. ii) It is controlled by forebrain. (1 Mark) Salivation on sight of food i) It is a reflex/involuntary action. ii)It is controlled by medulla in the hind brain. (1 Mark) (any other suitable difference)
Sunil unconsciously touched the hot iron rod and immediately withdrew his hand. Which type of action is involved ? Also define this action. Draw a flow chart to show the path followed for this action.
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• Reflex action (½ Mark) • An automatic and quick response to a stimulus which does not involve thinking. (½ Mark) • Stimulus $\rightarrow$ Receptor $\rightarrow$ sensory neuron $\rightarrow$ relay neuron (spinal cord) $\rightarrow$ Motor neuron $\rightarrow$ effector (muscle) response. (1 Mark)
Human brain has various parts or regions that help in different actions, responses and coordination. From the following, identify the part responsible for precision of voluntary actions :
Read the following passage and answer the questions that follow : A middle-aged person is facing some cognitive changes in himself. His early symptoms included mild forgetfulness. For example, forgetting where he left his mobile or failing to find words to complete his sentences. He was facing problems in driving a car, climbing up and down the stairs, inserting a plug into an outlet. He slowly developed a sad mood and anxiety. (a) What are voluntary actions ? (b) Which part of the brain is responsible for precision of voluntary actions?
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(a) Actions which are controlled by forebrain / Actions which are under our control and are performed according to our will. (1 Mark) (b) Cerebellum. (1 Mark)
Walking in a straight line and riding a bicycle are activities which are possible due to coordination of which part of the brain ? (Part of the Brain) (Name of the area of the Brain)
Following are the statements about the different parts of the brain. Select the correct statements. (i) The thinking part of the brain is the forebrain. (ii) Centres for smell, hearing, memory, sight are located in forebrain. (iii) Salivation, vomiting, blood pressure are controlled by medulla in the hind brain. (iv) Cerebellum does not control the posture and balance of the body.
From the given situations, identify 'Chemotropic' and 'Geotropic' movements in parts of plants, respectively : (i) Growth of pollen tube towards ovule. (ii) Movement of sunflower towards sunlight. (iii) Movement of root towards Earth/Gravity. (iv) Movement of leaves due to breeze. Choose the correct option :
Attempt either subpart (a) or (b) : OR (b) Explain how the pea plant climbs up the support by means of tendrils.
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(b)Tendrils of pea plant are sensitive to touch. When they come in contact with any support, the part of the tendril in contact with the object does not grow as rapidly as the part of the tendril away from the object. This causes the tendril to circle around the object and thus help in climbing the pea plant. (2 Marks)
Which of the plant hormones are responsible for the following processes ? (i) Promote cell division (ii) Inhibition of growth (iii) Detection of light (iv) Wilting of leaves
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(i) Cytokinin (½ Mark) (ii) Abscisic acid/ ABA (½ Mark) (iii) Auxin (½ Mark) (iv) Abscisic acid/ ABA (½ Mark)
Plants exhibit movements in response to various environmental stimuli to adopt and survive in their surroundings. These movements, influenced by external factors such as light, gravity, water and chemicals are regulated by specific plant hormones. For example, the differential growth of plant parts allows them to bend, grow or orient themselves in particular directions. Roots and shoots often show contrasting response to the same stimulus, highlighting the complex mechanisms involved in plant growth and development. (a) Why is hydrotropism essential for plants ? (b) What role does auxin play in the growth of plants ? (c) Differentiate between movement shown by the sensitive plant and tropic movement by plants (Two points). OR (c) How does movement of roots differ from that of shoots in response to gravity and light ?
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(a) Due to hydrotropism, the roots grow towards area of water availability so that they can absorb water and minerals. (1 Mark) (b) Auxins promote cell elongation / Auxin regulates the tropic responses like bending (growth) of stem towards light. (1 Mark) (c) begin{tabular}{|l|l|} hline textbf{Movement by sensitive plants} & textbf{Tropic Movements by plants} hline Non-directional & Directional hline Fast & Slow hline Growth independent movement & Growth related hline end{tabular} (Any two points and any other difference) (2 Marks) (c) begin{tabular}{|l|l|} hline textbf{Movement of Roots} & textbf{Movement of Shoots} hline Gravity: Grows towards gravity / Positive geotropism & Gravity: Grows away from gravity / Negative geotropism hline Light: Grows away from light / Negative phototropism & Light: Grows towards light/ Positive phototropism hline end{tabular} (2 Marks)
Assertion (A) : In case of iodine deficiency in our diet, there is a possibility that we might suffer from goitre. Reason (R) : One of the symptoms of goitre is swelling of neck.
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(B) / Both A and R are correct but R is not the correct explanation for A (1)
A squirrel in a scary situation requires its body to prepare for either ‘fight or flight' to save itself. State the immediate changes that will take place in its body so that it can face the situation.
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Squirrel shows fight or flight response -Release of adrenaline, heart beats faster, more supply of oxygen to muscles (limb muscles), reduced blood supply to digestive system and skin, contraction of rib muscles and diaphragm, increased breathing rate. (2 Marks)
(a) "The timing and the amount of hormone secreted by a gland are regulated in the human body." Justify this statement with the help of an example.
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(a) The timing and amount of hormone released are regulated by feedback mechanism. For example, if the sugar levels in the blood rise, they are detected by the cells of the pancreas which respond by producing more insulin. As the blood sugar level falls, insulin secretion is reduced. (Any other suitable example) (2 Marks) OR (b) * Electrical impulse reaches only those cells that are connected by nervous tissue, not each and every cell in the animal body. (1 Mark) * Once an electrical impulse is generated in the cell and transmitted, the cell will take some time to reset its mechanism before it can generate and transmit a new impulse. / Transmission of electrical impulses is not a continuous process. (1 Mark)
What are hormones ? State any one function of the following hormones : (i) Insulin (ii) Adrenaline
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Hormones are chemical messengers produced by endocrine glands that travel through blood stream to regulate various functions of the body. (1) (i) Regulates blood-sugar level. (½) (ii) Prepares body for dealing with stress. (½)
Varun is diabetic. His latest ultrasound reports showed a blockage in his pancreatic duct. How will this affect the dual functioning of the pancreas ?
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• As his pancreatic duct is blocked, enzymes for digestion will not be transported to small intestine / The blockage will cause difficulty in digestion of proteins, carbohydrates and fats. (1 Mark) • Insulin secretion is already affected. (1 Mark)
(a) Mention the gland and the hormone secreted by it in scary situation in human beings. (b) Write two responses that enable the human body to be ready to deal with such situation.
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(a) • Adrenal gland (½ Mark) • Adrenaline (½ Mark) (b) Responses (any two): • Adrenaline acts on the heart and makes the heart beats faster to provide oxygen to the muscles. • The blood supply to skin and digestive system is reduced due to contraction of muscles of arteries to divert the blood through skeletal muscles. • Breathing rate increases due to contraction of diaphragm and rib muscles. (1 + 1 Marks)
Read the following passage and answer the questions that follow : In many animals including humans, adrenaline hormone prepares for scary situation. The target organs on which it acts include the heart. The blood to the digestive system and skin is reduced, but the heart beats faster and breathing rate also increases. All these responses together enable the animal body to deal with such scary situation. (a) Attempt either subpart (i) or (ii) : (i) Name the gland that secretes adrenaline hormone. How does it enable the animal body to deal with a scary situation ? OR (ii) Why is the blood to the digestive system and skin reduced ? (b) Why is it important for us to have iodised salt in our diet? (c) Why does a doctor advise some persons to take less sugar in their diet?
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(a) (i) • Adrenal glands (½ Mark) • Adrenaline hormone is secreted directly into the blood and carried to different body parts. This makes heart beat fast resulting in supply of more oxygen to our muscles. The breathing rate also increases because of the contractions of the diaphragm and the rib muscles. These responses together enable the animal body to be ready to deal with scary situation. (1½ Marks) (a) (ii) The blood to the digestive system and skin is reduced due to contraction of muscles around small arteries in these organs to divert the blood to our skeletal muscles for more energy. (2 Marks) (b) Iodised salt contains iodine which is necessary for the thyroid gland to make thyroxin hormone. (1 Mark) (c) Because they are suffering from diabetes i.e. having high sugar level in their blood causing harmful effects / Insulin secretion is less. (1 Mark)