What is the role of the brain in reflex action?
[question] Question. What is the role of the brain in reflex action? [/question] [solution] solution: The reflexes which involve only the spinal cord are called spinal reflexes.The spinal reflexes are produced in the spinal cord but the message of reflex action taken also goes to reach the brain where the thinking process occurs. Some reflex arcs involve the brain, rather than the spinal cord only.They are called cerebral reflexes.Closing of eyes, when exposed to flash of light and salivation at...
Read More →How do we detect the smell
[question] Question. How do we detect the smell of an agarbatti (incense stick)? [/question] [solution] solution: When agarbatti burns, its pleasant small is detected by the olfactory receptor present inside the nose.The action of smell generate the electrical impluse which are carried to hypothalamus of brain thus we detect the smell of agarbatti. [/solution]...
Read More →Which do you think is a more basic characteristic for classifying organisms?
[question] Question. Which do you think is a more basic characteristic for classifying organisms? (a) The place where they live. (b) The kind of cells they are made of Why? [question] [solution] Solution: The kind of cells that living organisms are made up of is a more basic characteristic for classifying organisms, than on the basis of their habitat. This is because on the basis of the kind of cells, we can classify all living organisms into eukaryotes and prokaryotes. On the other hand, a habi...
Read More →Which part of the brain maintains posture
[question] Question. Which part of the brain maintains posture and equilibrium of the body? [/question] [solution] solution: Cerebellum. [/solution]...
Read More →What happens at the synapse
[question] Question. What happens at the synapse between two neurons ? [/question] [solution] solution: The neurons lie end to end in a chain to transmit the impulses in an animal body. The neurons are not connected. There occurs a very minute gap between terminal portion of axon of one neuron and dendron of the other neuron. This gap is called synapse. At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the gap (synapse), and start a simi...
Read More →What is the difference between a reflex
[question] Question. What is the difference between a reflex action and walking? [/question] [solution] solution: [/solution]...
Read More →Complete the table :
[question] Question. Complete the table : [/question] [solution] Solution: (i) Parenchyma (ii) Sclerenchyma (iii) Phloem. [/solution]...
Read More →How does the cork act as a protective tissue ?
[question] Question. How does the cork act as a protective tissue ? [/question] [solution] Solution: Cork acts as a protective layer because its cells are dead, filled with tannins, resin and air, impermeable due to deposition of suberin over the cell walls and absence of intercellular spaces. It is insulating (heat proof), fire proof, shock proof, water proof and repellent to microbes and animals. [/solution]...
Read More →There are many similarities in the way in which the modern world forced changes in the lives of pastoral communities in India and East Africa.
[question] Question. There are many similarities in the way in which the modern world forced changes in the lives of pastoral communities in India and East Africa. Write about any two examples of changes which were similar for Indian pastoralists and the Massai herders. [/question] [solution] Solution: There are many similarities in the way in which the modern world forced changes in the lives of pastoral communities in India and East Africa. Two changes that were similar for Indian pastoralists...
Read More →Compare the functioning of alveoli in the lungs
[question] Question. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning. [solution] solution: [/solution]...
Read More →What is the role of epidermis in plants ?
[question] Question. What is the role of epidermis in plants ? [/question] [solution] Solution: (i) Protection, (ii) Regulation of transpiration, (iii) Formation of insulating stationary air layer with the help of hair. (iv) Exchange of gases. [/solution]...
Read More →Explain why nomadic tribes need to move from one place to another.
[question] Question. Explain why nomadic tribes need to move from one place to another. What are the advantages to the environment of this continuous movement? [/question] [solution] Solution: Nomadic tribes need to move from one place to another because of seasonal changes. They seek to make effective use of pastures available in different areas. Many factors are taken into consideration to initiate movement to or from an area. These factors are availability of water and pasture, smooth movemen...
Read More →Name the regions in which parenchyma tissue is present.
[question] Question. Name the regions in which parenchyma tissue is present. [question] [solution] Solution: It occurs in almost all nonwoody parts of the plants – cortex, pith, medullary rays of stem, cortex and pith of root, chlorenchyma of leaves, flowers, pith of fruits, etc. Epidermis is special type of parenchyma. [/solution]...
Read More →What are the differences between the transport
[question] Question. What are the differences between the transport of materials in xylem and phloem? [/question] [solution] solution: [/solution]...
Read More →Solve 2x + 3y = 11 and 2x – 4y = – 24
[question] Question. Solve $2 x+3 y=11$ and $2 x-4 y=-24$ and hence tind the value of ' $m$ ' for which $y$ $=m x+3$ [/question] [solution] Solution: 2x + 3y = 11 ......(i) 2x – 4y = –24 ......(ii) Subtract equation (ii) from (i), we get 2x + 3y – 2x + 4y = 11 + 24 7y = 35 y = 5 Substituting value of y in equation (i), we get 2x + 3 × 5 = 11 2x = 11 – 15 $x=-\frac{4}{2}=-2$ Now, x = –2, y = 5 Puting value of x & y in y = mx + 3 5 = –2m + 3 2 = –2m m = –1 [/solution]...
Read More →Why are forests affected by wars?
[question] Question. Why are forests affected by wars? [/question] [solution] Solution: Forests are affected by wars on account of a variety of reasons. During the World Wars, Britain was ruthless in cutting down forests in India for war needs. To avoid Japan the profits from the forest industry, the Dutch destroyed saw mills and teak logs in Java. This blind destruction and cutting down of forests to fulfill national war requirements affects forests as they get depleted rapidly and are slow to ...
Read More →Identify the types of tissue in the following : bark of tree,
[question] Question. Identify the types of tissue in the following : bark of tree, vascular bundle, skin, bone, lining of kidney tubule. [/question] [solution] Solution: Bark of Tree : Cork (Protective tissue), Vascular Bundle : Complex or vascular tissues, xylem and phloem. Skin : Epithelial tissue, Bone : Connective tissue with solid matrix, Lining of Kidney tubule : Epithelial tissue. [/solution]...
Read More →Between 1880 and 1920, forest cover in the Indian subcontinent declined by 9.7 million hectares,
[question] Question. Between 1880 and 1920, forest cover in the Indian subcontinent declined by 9.7 million hectares, from 108.6 million hectares to 98.9 million hectares. Discuss the role of the following factors in this decline: Railways Shipbuilding Agricultural expansion Commercial farming Tea/Coffee plantations Adivasis and other peasant users [/question] [solution] Solution: (a) Railways: These were a necessary mode of transport for colonial trade and movement of troops. To run the locomot...
Read More →Describe double circulation of blood in human beings.
[question] Question. Describe double circulation of blood in human beings. Why is it necessary? [/question] [solution] solution: Double circulation In double circulation, the blood passes twice through the heart to supply once to the body (i) Systemic circulation In this, blood completes its circulation from left ventricle to right auricle through the body organs.(systemic organs) Oxygenated blood from lungs $\rightarrow$ heart $\rightarrow$ Systemic arteries $\rightarrow$ Body parts $\rightarro...
Read More →Name the following
[question] Question. Name the following : (a) Tissue that forms the inner lining of our mouth. (b) Tissue that connects muscle to bone in humans. (c) Tissue that transports food in plants. (d) Tissue that stores fat in our body. (e) Connective tissue with a fluid matrix. (f) Tissue present in the brain. [/question] [solution] Solution: (a) Epithelial tissue (b) Tendon (c) Phloem (d) Adipose (e) Blood (f) Nervous tissue [/solution]...
Read More →What would be the consequences of a deficiency
[question] Question. What would be the consequences of a deficiency of haemoglobin in our bodies? [/question] [solution] solution: Haemoglobin is the respiratory pigment that transports oxygen to the body cells for cellular respiration. Deficiency of haemoglobin in blood lead to deficiency of oxygen in the body cells which can lead to a disease called anaemia. [/solution]...
Read More →What are the similarities between colonial management of the forests in Bastar and in Java?
[question] Question. What are the similarities between colonial management of the forests in Bastar and in Java? [/question] [solution] Solution: The similarities between colonial management of the forests in Bastar and in Java are many. The Dutch started colonial forest management in Java just as the British had done in India, for timber. The villagers in Bastar were allowed to stay on in reserved forests if they provided free labour for timber firms; likewise, the blandongdiensten system in Ja...
Read More →Solve the following pair of linear equations by the substitution method.
[question] Question. Solve the following pair of linear equations by the substitution method. (i) x + y = 14, x – y = 4 (ii) $\mathrm{s}-\mathrm{t}=3, \frac{\mathbf{s}}{\mathbf{3}}+\frac{\mathbf{t}}{\mathbf{2}}=\mathbf{6}$ (iii) 3x – y = 3, 9x – 3y = 9 (iv) 0.2x + 0.3y = 1.3, 0.4x + 0.5y = 2.3 (v) $\sqrt{\mathbf{2}} \mathbf{x}+\sqrt{\mathbf{3}} \mathbf{y}=\mathbf{0}, \sqrt{\mathbf{3}} \mathbf{x}-\sqrt{\mathbf{8}} \mathbf{y}=\mathbf{0}$ (vi) $\frac{3 x}{2}-\frac{5 y}{3}=-2, \frac{x}{3}+\frac{y}{2...
Read More →Draw a labelled diagram of a neuron.
[question] Question. Draw a labelled diagram of a neuron. [/question] [solution] Solution: [/solution]...
Read More →How are the alveoli designed to maximise
[question] Question. How are the alveoli designed to maximise the exchange of gases? [/question] [solution] solution: Alveoli are small pouches or sacs. Large number of alveoli occur inside each lung. The whole surface of an alveolus functions as respiratory surface. Due to large number of alveoli in each lung, a very large area of respiratory surface becomes available (about $80 \mathrm{~m}^{2}$ ) for exchange of gases. The walls of alveoli are very thin and they are surrounded by blood capilla...
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