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Hydrogen (H), a colourless, odourless, tasteless, flammable gaseous substance that is the simplest member of the family of chemical elements. The hydrogen atom has a nucleus consisting of a proton bearing one unit of positive electrical charge; an electron, bearing one unit of negative electrical charge, is also associated with this nucleus. Under ordinary conditions, hydrogen gas is a loose aggregation of hydrogen molecules, each consisting of a pair of atoms, a diatomic molecule, H2. The earliest known important chemical property of hydrogen is that it burns with oxygen to form water, H2O; indeed, the name hydrogen is derived from Greek words meaning “maker of water.”

1.Aerobic organism →aerobic respiration pathway needs oxygen → sufficient intake of oxygen is necessary.

2.Glucose is a 6 carbon compound → C6H12O6

3. Pyruvate → 3-carbon molecule.

4. What is glycolysis?

Glucose is initially converted into two molecules of pyruvate through a process called glycolysis in the cytoplasm.

 (This involves a series of enzymatic reactions, ultimately yielding a 3-carbon compound, pyruvate.)

5. Why is the rate of breathing in aquatic organismsis much faster than in terrestrial organisms?

The amount of dissolved oxygen is low compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic organismsis is much faster than in terrestrial organisms.

6. How is air taken into the body in aerobic terrestrial organisms?

Air is taken into the body through the nostrils. The passage has fine hairs and is lined with mucus.

7 How is air taken into the body in aerobic terrestrial organisms?

In aerobic terrestrial organisms air is taken into the body (through nostrils) through the process of inhalation. 

8. What are alveoli?

Alveoli are tiny, air-filled sacs within the lungs where the exchange of gases takes place. The walls of the alveoli contain an extensive network of blood-vessels.

The alveoli provide a surface where the exchange of gases can take place. 

9. Why is carbon dioxide transported in dissolved form?

The respiratory pigment hemoglobin which has a very high affinity for oxygen. Carbon dioxide is more soluble in water than oxygen is and hence is mostly transported in the dissolved form in our blood.

10. Which is the respiratory pigment?

[Hemoglobin (US)/ Haemoglobin (🇬🇧 British English (used in UK/AU/NZ)]

Hemoglobin is the primary respiratory pigment in humans and many other animals. It is a protein found in red blood cells that binds with oxygen in the lungs, transporting it to tissues throughout the body. Hemoglobin also helps carry carbon dioxide, produced by cells, back to the lungs for exhalation.

11. What is the function of blood?

Blood transports food, oxygen and waste materials in our body.

12. Give an example for an anaerobic organism.

Yeast

13. Where is glucose converted into pyruvate?

 In cytoplasm.

14. Does anaerobic respiration take place in humans? Where does it take place? What is it called?

When cellular respiration takes place in human muscle cells without oxygen, it is known as anaerobic respiration. 

15. What is the end product of anaerobic respiration in human muscle cells?

lactic acid,

16. Which chemical is responsible for temporary muscle fatigue when anaerobic respiration in human muscle cells takes place?

Lactic acid,

17. What is anaerobic respiration?

Anaerobic respiration is a type of cellular respiration that occurs in the absence of oxygen. 

18. When does anaerobic respiration take place in human beings?

Anaerobic respiration in human beings typically occurs during intense physical activities or when there is insufficient oxygen supply to meet the energy demands of cells. During strenuous exercise, muscles may experience oxygen depletion, leading to anaerobic conditions. In such situations, cells undergo anaerobic respiration, producing energy through glycolysis and lactic acid fermentation. This process helps sustain energy production temporarily when the oxygen supply is inadequate. The buildup of lactic acid can contribute to muscle fatigue and soreness.

19. Is anaerobic respiration high energy giver?

Anaerobic respiration is generally less efficient in terms of energy production compared to aerobic respiration. While it provides a quick burst of energy, anaerobic respiration (specifically lactic acid fermentation in humans) yields fewer ATP (adenosine triphosphate) molecules per glucose molecule than aerobic respiration.

Aerobic respiration, which occurs in the presence of oxygen, is a more efficient process and yields a higher amount of ATP. However, anaerobic respiration becomes necessary in situations where oxygen is limited or unavailable, such as during intense exercise or in certain microenvironments within the body.

20. What are the components of blood?

Blood consists of plasma, red blood corpuscles, White blood corpuscles and platelets.

21. What are the components of blood?

Blood is composed of several components, including:

1. **Red Blood Cells (RBCs):** Responsible for carrying oxygen to tissues and organs. They contain the pigment hemoglobin, which gives blood its red color.

2. **White Blood Cells (WBCs):** Part of the immune system, they help defend the body against infections and foreign substances.

3. **Platelets:** Small cell fragments that play a crucial role in blood clotting and wound healing.

4. **Plasma:** The liquid portion of blood, composed of water, electrolytes, proteins, hormones, and waste products. It serves as a medium for transporting cells, nutrients, and hormones throughout the body.

These components work together to maintain various physiological functions, including oxygen transport, immune response, and blood clotting.

22. What is the function of plasma?

Plasma transports food, carbon dioxide and nitrogenous wastes in dissolved form.

23. What is the function of red blood corpuscles?

Red blood corpuscles transport oxygen.

24. What's the function of platelet cells?

Platelet cells helps in blood clotting at the points of injury.

25. What is the use of separation of heart into left and right sides?

The separation of the right side and the left side of the heart is useful to keep oxygenated and deoxygenated blood from mixing. This allows:

(i) a highly efficient supply of oxygen to the body.

(ii) This is useful in animals that have high energy needs, such as birds and mammals, which constantly use energy to maintain their body temperature.

26. What is the use of separation of heart into left and right sides?

The separation of the heart into left and right sides allows for the efficient circulation of oxygenated and deoxygenated blood. The right side pumps blood to the lungs for oxygenation, while the left side pumps oxygenated blood to the rest of the body. This division ensures that oxygen-rich and oxygen-poor blood do not mix, optimizing the distribution of oxygen throughout the body.

26. Fishes have only two chambers in their hearts, and blood goes only once through the heart in the fish during one cycle of passage through the body. Why?

Fish have a two-chambered heart and a single-loop circulatory system because their lifestyle and respiratory needs are less complex than those of mammals and birds. In the fish's aquatic environment, the gills efficiently extract oxygen from water, and the two-chambered heart is sufficient to pump oxygen-poor blood to the gills for oxygenation and then circulate it through the body. This streamlined system meets the metabolic demands of fish in their underwater habitats.

27. Fishes have only two chambers in their hearts, and blood goes only once through the heart in the fish during one cycle of passage through the body 

Exactly. Fish have a two-chambered heart with one atrium and one ventricle. Blood is pumped through the gills for oxygenation and then circulated through the rest of the body in a single circuit. This is known as a single-loop circulatory system, as opposed to the double-loop system found in mammals and birds with a four-chambered heart.

28. What is double circulation?

In vertebrates like birds and mammals blood goes through the heart twice during each cycle. This is known as double circulation.

29. Mention the types of blood vessels.

There are three main types of blood vessels: arteries, veins, and capillaries.

30. What is the function of arteries?

Arteries carry oxygenated blood away from the heart, 

31. What is the function of veins?

Veins carry deoxygenated blood back to the heart,

32. What is the function of capillaries?

capillaries facilitate the exchange of nutrients and gases between the blood and tissues.

33. Differentiate between arteries and veins.

Arteries carry oxygenated blood away from the heart to various parts of the body, while veins transport deoxygenated blood back to the heart. Arteries typically have thicker walls and a more elastic structure to withstand high blood pressure, while veins have thinner walls and contain valves to prevent the backflow of blood. Additionally, arteries often appear red, while veins appear blue due to the oxygenation status of the blood they carry.

34. What is lymph?

Lymph is a colorless fluid that circulates through the lymphatic system. It is derived from interstitial fluid that surrounds tissues and plays a crucial role in immune function by carrying white blood cells and filtering out impurities, toxins, and foreign particles. Lymph nodes, part of the lymphatic system, act as filters to trap and destroy harmful substances present in the lymph.

35. What is lymph?

It is similar to the plasma of blood but colourless and contains less protein.

36. What does lymph carry?

Lymph carries digested and absorbed fat from intestine and drains excess fluid from extra cellular space back into the blood.

37. What is transpiration?

The loss of water in the form of vapour from the aerial parts of the plant.

38. What are the uses of transpiration?

Transpiration helps in the absorption and upward movement of water and minerals. And helps in temperature regulation. Suction created by transpiration and difference in the ion concentration created between soil and root are responsible for the transportation of water.

39. What is the function of xylem?

 Xylem transports water and minerals obtained from the soil.

40. What is the function of phloem?

The phloem transports products of photosynthesis from the leaves to other parts of the plant.

41. What is translocation?

Transport of soluble products of photosynthesis.

42. What is excretion?

Removal of harmful metabolic wastes from the body.

43. Describe the excretory system of human beings very briefly.

The excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra.

44. What is the function of kidneys?

The kidneys filter blood to remove waste products and excess fluid, regulating electrolytes, maintaining proper blood pressure, and producing hormones that help in red blood cell production and calcium metabolism.

45. What is the function of kidneys?

Nitrogenous wastes such as urea and uric acid are removed from blood in the kidneys.

46. Are nitrogenous wastes such as urea and uric acid removed from blood in the kidneys?

Yes, that's correct. The kidneys play a crucial role in filtering nitrogenous wastes, such as urea and uric acid, from the blood. These waste products are then excreted as urine, helping maintain the body's overall balance of electrolytes and waste elimination.

47. What are the filtration units of kidney?

Nephrons are filtration units present in the kidney.

48. What are the filtration units of kidney?

The filtration units of the kidney are called nephrons. Each kidney contains approximately one million nephrons, and they are responsible for filtering blood, removing waste products, and regulating fluid and electrolyte balance.

49. Explain excretion in plants.

Excretion in Plants: Plants use different strategies for excretion.

(i) Plants get rid of excess of water by transpiration. (ii) Waste products are stored in cellular vacuoles.

(iii) Waste products may be stored in leaves that fall off.

(iv) Resins and gums are stored in old xylem.

(v) Some waste substances excreted into the soil from roots.

50. Explain excretion in plants.

In plants, excretion involves the removal of waste substances produced during metabolic processes. This is primarily achieved through several mechanisms:

1. **Transpiration:** Plants release water vapor through tiny pores called stomata on their leaves. This process helps in the elimination of excess water and some dissolved minerals.

2. **Resin and Guttation:** Some plants excrete waste substances in the form of resins or through guttation. Resins often contain toxic substances and protect the plant from herbivores, while guttation is the exudation of water droplets containing dissolved substances.

3. **Senescence:** During aging or senescence, older leaves or plant parts may undergo programmed cell death, leading to the shedding of these parts. This serves as a way for the plant to get rid of older tissues containing accumulated waste products.

4. **Root Exudates:** Plants release substances into the soil through their roots, a process known as root exudation. This helps in modifying the soil environment and may involve the release of certain metabolic by-products.

Overall, excretion in plants is not as complex as in animals, but these mechanisms help them maintain internal balance and cope with metabolic waste.

51. Functions of cerebellum of human brain 

The cerebellum plays a crucial role in coordinating voluntary movements, maintaining balance, and refining motor skills. It also contributes to cognitive functions like attention, language, and emotional regulation.

52. A person writes a very good handwriting. Which part of the brain is responsible for this?

Handwriting involves fine motor control, and the cerebellum, located at the back of the brain, plays a significant role in coordinating these precise movements.

53. I'm fed up with jerky movements of a drunkard? Which part of the brain is responsible for this drawback?

The cerebellum is responsible for coordinating smooth and controlled movements. Excessive alcohol consumption can impair the function of the cerebellum, leading to jerky and uncoordinated movements in drunk individuals.

54. My son is a very good dancer which part of the brain is a responsible for this?

Dancing involves complex motor coordination and rhythm. The cerebellum, along with other brain regions such as the motor cortex, basal ganglia, and sensory areas, contributes to the ability to dance skillfully.

55. What are the functions of pons in the human brain?

The pons, located in the brainstem, serves several important functions. It helps regulate breathing by controlling the respiratory centers, assists in facial movements and sensation, and plays a role in certain aspects of sleep and arousal. Additionally, it serves as a bridge connecting different regions of the brain.

56. What are the functions of medulla oblongata in human brain?

The medulla oblongata, located in the brainstem, is crucial for various involuntary functions essential for survival. It regulates vital functions such as heartbeat, breathing, blood pressure, and reflexes like swallowing, coughing, and vomiting. The medulla helps maintain homeostasis and serves as a vital connection between the spinal cord and higher brain centers.

57. What are autotrophs?

Autotrophs are organisms that can produce their own food using inorganic substances and energy sources, typically through processes like photosynthesis or chemosynthesis. They are self-sustaining and do not rely on external sources for organic nutrients. Plants are a common example of autotrophs as they utilize sunlight to convert carbon dioxide and water into glucose during photosynthesis.

58. What is nutrition?

Nutrition is the process by which living organisms obtain and utilize the substances necessary for growth, maintenance, and repair of their body tissues. It involves the intake, digestion, absorption, and utilization of nutrients such as carbohydrates, proteins, fats, vitamins, and minerals. Proper nutrition is essential for the functioning and well-being of an organism.

59. What is autotrophic nutrition?

Autotrophic nutrition is a type of nutrition where organisms produce their own organic compounds from inorganic substances, using external energy sources. Autotrophs, such as plants and certain bacteria, are capable of synthesizing their own food through processes like photosynthesis or chemosynthesis. In photosynthesis, for example, plants use sunlight to convert carbon dioxide and water into glucose, a process that sustains their energy needs and provides a source of organic nutrients.

60. What are stomata?

Tiny pores present on the surface of the leaves are called stomata.

61. What is the function of stomata? 

Gaseous exchange takes place in the leaves through stomata for the purpose of photosynthesis. Since large amounts of water can also be lost through these stomata, the plant closes these pores when it does not need carbon dioxide for photosynthesis.

62. What is meant by heterotrophic nutrition?

Heterotrophic nutrition is a type of nutrition in which organisms obtain organic compounds from other living organisms. Unlike autotrophs, which can produce their own food, heterotrophs are unable to synthesize organic molecules from inorganic sources. They rely on consuming other organisms, whether plants, animals, or microorganisms, to obtain the necessary nutrients for their growth and energy needs. Humans, animals, fungi, and many bacteria are examples of organisms that exhibit heterotrophic nutrition.

63.Name the device used to measure the rate of current in a circuit.

The device used to measure the rate of current in a circuit is called an ammeter.

64. What is myopia?

Myopia, commonly known as nearsightedness, is a refractive error of the eye where close objects can be seen clearly, but distant objects appear blurred. This occurs when the eyeball is too long or the cornea (the front part of the eye) has too much curvature. Corrective lenses, such as glasses or contact lenses, are often used to help individuals with myopia see distant objects more clearly. In some cases, refractive surgery may be an option.

65. What is myopia?

Myopia is also known as near-sightedness. This is a common type of refractive error, in which the person suffers from a condition where the objects, closer to the individual, appear clearly, but the distant objects appear to be blurry.

66. What is myopia? 

Myopia, also known as short-sightedness, is an eye disorder that occurs when the eye loses its ability to focus on far-off objects.

67. Write one of the main symptoms of myopia.

Squinting and frowning are one of the symptoms of myopia.

68. What is the formula to calculate the power of correcting lens for myopia?

What is the formula to calculate the power of correcting lens for myopia?

The formula to calculate the power of a correcting lens for myopia (nearsightedness) is:

\[ \text{Lens Power} = \text{Spherical Power} \]

The power is measured in diopters (D), and it represents the strength of the lens needed to correct the myopic vision. The spherical power for myopia is a negative value, indicating the concave nature of the lens required to diverge incoming light and bring distant objects into focus for the individual with myopia.

69. What are gustatory receptors?

Gustatory receptors are sensory cells responsible for detecting taste. Found on the taste buds, primarily on the tongue, these receptors help us perceive basic tastes like sweet, salty, sour, bitter, and umami.

70. What are olfactory receptors?

Olfactory receptors are sensory cells located in the nasal cavity that detect odors or smells. These receptors play a crucial role in our sense of smell, allowing us to perceive and distinguish various scents.

71. What is meant by synapse?

A synapse is a junction between two nerve cells, where signals are transmitted from one cell to another. 

72. What are the limitations of Dobereiner law of triads?

Dobereiner's Law of Triads, proposed in the early 19th century, arranged elements into triads where the middle element had an average atomic mass. However, it had limitations:

1. **Limited Applicability:** The law worked for some triads, but not all elements could be grouped into such sets. As more elements were discovered, the pattern broke down.

2. **Arbitrary Triads:** The selection of triads was somewhat arbitrary, and not all elements fit neatly into this grouping, leading to inconsistencies.

3. **Inaccuracy in Atomic Mass Prediction:** Dobereiner's method of predicting the atomic mass of the middle element as the average of the other two was imprecise, especially as more accurate atomic masses were determined later.

4. **No Explanation of Chemical Behavior:** The law didn't provide a theoretical basis for understanding the chemical behavior of elements within a triad.

Ultimately, advancements in the understanding of atomic structure and the development of the periodic table by Mendeleev and Moseley replaced Dobereiner's triads with a more systematic and accurate arrangement of elements.

73What is presbyopia?

Presbyopia is the gradual loss of the eye's ability to focus on nearby objects.

74. What is presbyopia?

Presbyopia is a common age-related condition where the natural lens of the eye loses its flexibility, making it difficult for individuals to focus on close objects. Typically, it becomes noticeable around the age of 40 and progresses with time. This condition affects the eye's ability to accommodate or adjust its focus, leading to difficulties in reading or performing tasks that require seeing things up close. Reading glasses or contact lenses with a prescription for near vision are commonly used to alleviate the effects of presbyopia.

75. What is presbyopia?

Presbyopia is the gradual loss of your eyes' ability to focus on nearby objects.

76. What is cataract?

A cataract is a clouding of the lens in the eye, leading to a gradual loss of vision.

77.What is cataract?

A cataract is a clouding of the lens in the eye, leading to a gradual loss of vision. The lens, which is usually clear, becomes cloudy over time, affecting the passage of light to the retina. Cataracts are often associated with aging, but they can also result from injury, certain medications, or underlying medical conditions.

Common symptoms of cataracts include blurred or cloudy vision, increased sensitivity to glare, difficulty seeing in low light, and seeing halos around lights. Surgical removal of the cloudy lens and replacement with an artificial lens is a common and effective treatment for cataracts, restoring clear vision for many individuals.

78. What is hypermetropia

Hypermetropia, also known as farsightedness, is a common refractive error in the eye. In hypermetropia, distant objects can be seen more easily than close ones because light entering the eye focuses behind the retina instead of directly on it. This occurs when the eyeball is too short or the cornea has too little curvature.

People with hypermetropia may experience difficulties with tasks that require close-up focus, such as reading or using a computer. Corrective lenses, such as glasses or contact lenses, are commonly prescribed to help redirect light onto the retina and improve close-up vision for individuals with hypermetropia.

79. What is myopia?

Myopia, commonly known as nearsightedness, is a refractive error in the eye where close objects are seen more clearly than distant ones. This occurs when the eyeball is too long or the cornea has too much curvature, causing light entering the eye to focus in front of the retina instead of directly on it.

People with myopia often have clear vision when looking at objects up close but struggle with distance vision. Eyeglasses or contact lenses with a prescription to diverge incoming light are typically used to correct myopia, allowing distant objects to come into focus on the retina. Additionally, some people opt for refractive surgeries, like LASIK, to correct myopia.

80.What is bifocal lens?

Bifocal lenses are eyeglass lenses with two distinct optical powers. The upper portion corrects distance vision, while the lower portion is for near vision. They're often prescribed for individuals with presbyopia, a condition where the eye's ability to focus on close objects diminishes with age.

90. Observe the given figure. Identify the eye defect indicated in this figure.

(A) Presbyopia

(B) Hypermetropia

(C) Myopia

(D) Cataract

91 What is presbyopia?

Presbyopia is the gradual loss of the eye's ability to focus on nearby objects. For most people, the near point gradually recedes and the far point comes closer. This defect is called presbyopia. As the person gets older, the power of accommodation of the eye decreases.

92. A light ray enters to rarer medium from a denser medium. Then the speed of that light ray

(A) decreases and bends towards the normal

(B) increases and bends away from the normal

(C) decreases and bends away from the normal

(D) increases and bends towards the normal

93. Refraction is the bending of the path of a light wave as it passes from one media to another media. It is caused by the change in speed experienced by the light ray. When a ray of light travels from a denser medium to a rarer medium, the ray will speed up and bend away from the normal.

94. The inner wall of the solar cooker is painted black. Because black colour

(A) reflects light

(B) converges solar rays

(C) prevents from rusting

(D) absorbs more heat

95. The inner wall of the solar cooker is painted black. Because black colour

The inner wall of the solar cooker is painted black because black absorbs more sunlight, converting it into heat energy, which enhances the cooking efficiency by promoting better absorption and retention of solar radiation.

96. What is rheostat?

A rheostat is a variable resistor that can be adjusted to control the flow of electric current in a circuit. It is often used to regulate the intensity of light in lamps or the speed of electric motors by changing the resistance in the circuit.

97. What is Resistance?

Resistance is defined as the property of the conductor which opposes the flow of electric current. It is also defined as the ratio of the voltage applied to the electric current flowing through it.

98. A rheostat is a variable resistor which is used to control current.

They are able to vary the resistance in a circuit without interruption. ... It uses only two connections, even when 3 terminals (as in a potentiometer) are present.

Variable resistance: As the name suggests, the variable resistor changes in resistance but it is according to the current flowing in it. This helps in controlling the current by providing enough resistance to the circuit. Variable resistance also controls voltage across two devices.

99. In the left-hand rule, the middle finger represents the direction of the current. In the right-hand rule, the middle finger represents the direction of the induced current.

100. What is the second name for the Maxwell right hand thumb rule?

Answer: Maxwell's right-hand thumb rule is also known as the corkscrew rule.

101. What is speciation?

Speciation is an evolutionary process of the formation of new and distinct species. 

102. What is speciation?

Speciation is the process by which populations evolve to become distinct species. It often involves reproductive isolation, where groups no longer interbreed successfully, leading to genetic divergence over time. Factors like geographical barriers or genetic mutations can contribute to speciation.

II. Answer the following questions:

2×1=2

5. Write the symbols of the following components used in an electric circuit.

i) Rheostat 

ii) Wires crossing without joining

6. What does the thumb indicate in the right hand thumb rule ?

III. Answer the following questions:

2x2=4

7. Light enters from air to benzene having refractive index 1.50. Calculate the speed of light in benzene. (Speed of light in air: 3 x 108 ms¹)

OR

A concave lens has focal length of 12 cm. At what distance should the object from the lens be placed so that it forms an image at 9 cm from the lens?

8. Name the major constituent of biogas and write the properties of biogas.

OR

List the hazards of nuclear power generation.

IV. Answer the following questions:

3×3=9

9. State Ohm's law. On which factors does the resistance of a conductor depend? Mention the SI unit of electric power.

OR

State Joule's law of heating. How is fuse connected in the circuits ? Name the metal used in the filament and the gas filled in electric 

bulb.

Blood vessels:

i) Arteries: Carry blood away from the heart. (

Have thick, elastic walls. (Because blood flows with great pressure)

(ii) Veins: Brings the blood back to the heart.

Have thin walls. (Because blood flows with less pressure)

have valves. (To prevent the backward flow of blood)

iii) Capillaries: Bring the blood in contact with all the individual cells. 

have walls which are one-cell thick.