Question 1

The diagram shows a leaf on a plant.Which characteristic of life is represented by this diagram?

Accepted Answer

The given diagram represents a vital phenomenon i.e., Photosynthesis. Photosynthesis is a mode of autotrophic nutrition in plants. It is essential to all life on earth; both plants and animals depend on it. It is the only biological process that can capture energy that originates from sunlight and convert it into a chemical compound (glucose) that every organism uses to power its daily functions. Photosynthesis generally takes place in the leaves of plants. It is a multi-step process that requires sunlight, carbon dioxide (CO2​, found in the air), and water (H2​O, from the soil). After the process is complete, the plant releases oxygen into the air (O2​, essential for many living organisms) and produces the simple carbohydrate molecule of glucose, which can be used as an energy source by the plant, converted to starch and stored for a later energy source, or converted into other organic molecules such as fats, proteins and vitamins.

Question 2

The diagram shows an insect. What is the insect?1 insect has no wings ........................................... go to 2insect has wings ................................................ go to 32 legs longer than, or as long as the body ........... Alegs shorter than the body ................................. B3 abdomen long and thin ...................................... Cabdomen shorter and wider ............................... D

Accepted Answer

The body of an insect is divided into head, thorax, and abdomen. As clearly visible in the diagram, it has three pairs of walking legs — one pair on each thoracic segment.  The insect does not have wings and the legs of insect are shorter than its body. There are 7 abdominal segments. The abdomen is longer and wider as compared to the thorax.

Question 3

Which features are possessed by all plant cells?

Accepted Answer

. All plant cells possess cell wall. It provides a structural framework to support plant growth and acts as the first line of defense when the plant encounters pathogens..Chloroplasts are present in the cells of all green tissues of plants and algae. The inner stem cells and underground organs, such as the root system or bulb, contain no chloroplasts. Because no sunlight reaches these areas, chloroplasts would be useless.

Question 4

Which organ is part of the digestive system?

Accepted Answer

. The colon removes water and some nutrients and electrolytes from partially digested food. The remaining material, solid waste called stool, moves through the colon, is stored in the rectum, and leaves the body through the anus. The colon is part of the digestive system.. The larynx is the upper opening into the windpipe (trachea), the passageway to the lungs. It's a part of respiratory system. . The trachea is often called the windpipe. It's a part of respiratory system. . The urine travels from the kidneys to the bladder in two thin tubes called ureters. It's a part of excretory system.

Question 5

The diagram shows a test-tube containing clear jelly. A drop of blue ink is injected into the middle of the jelly.The blue colour of the ink spreads throughout the jelly.By which process does the blue ink spread through the jelly?

Accepted Answer

. The blue ink spreads through the jelly by diffusion.. Diffusion is the process by which molecules move from a region of higher concentration to a region of lower concentration.. In this diagram, when a drop of blue ink is added to the clear jelly, it occupies a particular position inside the jelly.. From there, every other point in the jelly is at a lower concentration of blue ink than the initial position occupied by it. So it starts moving to other points in the jelly, i.e, it diffuses throughout the jelly.. This diffusion continues till every point in the jelly is at a uniform concentration of the blue ink, hence turning the whole jelly blue.Therefore, the blue ink spreads through the jelly through diffusion.

Question 6

The apparatus shown was set up.Some hours later, the water in the beaker had turned blue, and the liquid in the glass tube had moved upwards.Which processes caused these changes?

Accepted Answer

Water turned blue - diffusion ; liquid in glass tube moved upwards - osmosis. Diffusion is the process by which molecules move from a region of higher concentration to a region of lower concentration. This diffusion continues till every point in the water is at a uniform concentration of the blue ink, hence turning the whole water blue.The concentration of water in the beaker is higher than the concentration of water in the glass tube. By the definition of osmosis, water always moves from an area of higher water concentration to lower water concentration through a semi-permeable membrane. Also, since the solvent molecules inside the tubing are less, water molecules from outside will rush in, leading to a rise in the water level. Therefore, liquid in glass tube moved upwards by the process of osmosis.

Question 7

Four solutions were tested to see whether they contained protein, starch or glucose.The colours of the solutions after the tests are recorded in the table.Which solution contained protein and glucose but not starch?

Accepted Answer

The biuret test is a chemical test that can be used to check for the presence of peptide bonds in a given analyte. A positive test is indicated by a purple color due to the copper ion complex with the amide group of the protein. Hence solution C and D have proteins.Now in the next step iodine test is conducted, Amylose in starch is responsible for the formation of a deep blue color in the presence of iodine. As shown in the table, solution  B and D turned blue-black, therefore we can conclude that solution A and C does not have starch. Benedict's test is a chemical test that can be used to check for the presence of reducing sugars (such as glucose) in a given analyte. Therefore, when reducing sugars are present in the analyte, the cupric ions (Cu2+) in Benedict's reagent are reduced to cuprous ions (Cu+). These cuprous ions form copper(I) oxide with the reaction mixture and precipitate out as a brick-red/orange coloured compound.Hence, it is quite evident that amongst the four solutions, solution C has proteins as well as glucose but it lacks starch.

Question 8

Small molecules are used as the basic units in the synthesis of large food molecules.Which statement is correct?

Accepted Answer

- Amino acids are the basic units of proteins, not carbohydrates.- Fatty acids are not the basic units of glycogen; glucose molecules are the basic units of glycogen.- Glycerol is a component of lipids (fats and oils), and it can combine with fatty acids to form triglycerides, which are the main constituents of oils.- Simple sugars (monosaccharides) are the basic units of carbohydrates, not proteins.So, the correct answer is that glycerol is a basic unit of oils.

Question 9

Which graph shows the effect of pH  on enzyme activity?

Accepted Answer

. The curve in option (c) correctly represents the effect of pH on enzyme activity. Enzyme shows its highest activity at a particular pH called the optimum pH. Activity declines both below and above the optimum value.This can be easily represented using the graph given in option (c). Changes in pH also alter the shape of an enzyme’s active site. Each enzyme work bests at a specific pH value. The optimum pH for an enzyme depends on where it normally works. As the pH increases so does the rate of enzyme activity. A continued increase in pH results in a sharp decrease in activity as the enzyme’s active site changes shape. It is now denatured.Therefore, option (c) is correct.

Question 10

The diagram shows an experiment to investigate the balance between respiration and photosynthesis. In which tube are photosynthesis and respiration taking place at the same time?

Accepted Answer

In tube A and B photosynthesis cannot take place as these tubes are covered with black polythene, which cuts off the sunlight which is essential for carrying out photosynthesis.Amongst tube C and D, tube D contains snail (an animal), although it carry out the process of respiration but it lacks the process of photosynthesis whereas tube C contains pond weed (a plant), plants carry out the process of photosynthesis as well as respiration.Hence the tube in which photosynthesis and respiration are taking place at the same time is tube C.

Question 11

The chart is used to find a person's recommended mass.For the data provided about body mass and height, which person would benefit most from the introduction of a calorie-controlled diet and regular exercise?

Accepted Answer

Body Mass Index (BMI) is a person's weight in kilograms (or pounds) divided by the square of height in meters (or feet). It is a useful measure of overweight and obesity.The given chart is used to find a person's recommended mass on the basis of his/her height.Let us consider person A, the height of the person is 1.55m, from the chart we can say that this person has an ideal weight i.e., around 40-50 kg.Person B has slightly low body mass, as for a person with height 1.75m, the ideal weight is around 60 kg. Person C has an ideal body weight i.e., around 70kg.Person D is moderately obese, as compared to height the ideal weight should be around 60-70kg, but the person weights 90kg. Therefore person D will be benefitted most from the introduction of a calorie-controlled diet and regular exercise.

Question 12

The following statements are about enzymes.1 enzymes are catalysts2 enzyme are proteins3 enzymes are used up during chemical reactionsWhich statements are correct?

Accepted Answer

Enzymes are proteins comprised of amino acids linked together in one or more polypeptide chains. Functionally enzymes are biological catalysts (also known as biocatalysts) that speed up biochemical reactions in living organisms.  As catalysts, enzymes are only required in very low concentrations, and they speed up reactions without themselves being consumed during the reaction. Hence, statement 1 and 2 are correct and statement 3 is incorrect.

Question 13

The diagram shows a human tooth with an area of decay.What is likely to have caused the decay?

Accepted Answer

Bacteria in the mouth feed on sugary, starchy foods and drinks (fruit, candy, bread, sodas, juice and milk). The bacteria convert these carbohydrates into acids.Bacteria, acid, food and saliva mix to form plaque. This sticky substance coats the teeth.Without proper brushing and flossing, acids in plaque dissolve tooth enamel, creating cavities, or holes, resulting in tooth decay.

Question 14

A celery stalk was placed into a beaker of blue dye. When the dye reached the leaves, the stalk was taken out and a section was cut, as shown in the diagram.Which diagram shows the appearance of the cut end of the stalk?

Accepted Answer

The dissolved blue dye moves like water through the conducting elements of plants (i.e., xylem tubes) into the celery stalk and leaves. Option A is not correct as it does not show presence/movement of dye.In option C, the outlined portion of the cut end of stalk is shown colored, indicating the movement of dye , but the movement of dye takes place through xylem which is located towards the inner side. Hence option C is also incorrect.Option D shows the movement of dye through entire region of stalk region which is again not correct.Therefore the correct option is B, as it precisely shows the movement of dye through xylem. In a mature plant xylem is stacked end to end in the center of the plant, forming a vertical column that conducts water and minerals absorbed by the roots upward through the stem to the leaves.

Question 15

The table shows the rate of water flow through a tree over a 12 hour period.What conclusion can be drawn from the table?

Accepted Answer

From the given table the following conclusions can be drawn-1. From 7:00 to 11:00 hours (from morning to afternoon), the rate of flow of water increases at a constant rate of 10 cm/hour. (Therefore, option A is incorrect)2. The greatest increase in rate of flow in a two-hour period is between 11:00 and 13:00 hours (peak noon), i.e., 55 cm/hour. (Option B is correct)3. In late evening the rate of flow of water started decreasing but is not completely stopped.We are not provided with the data for night hours, hence from given information it cannot be said that whether water does/ or does not flow up through a tree at night. (Therefore option C is incorrect).In general, assuming the dewpoint or absolute humidity does not change, the relative humidity will be highest in the early morning when the air temperature is coolest, and lowest in the afternoon when the air temperature is highest. But we are not provided any information about the environmental conditions, therefore we cannot directly conclude about how water flow is affected by humidity from the given data. Therefore option D cannot be marked as correct.

Question 16

The diagram shows a section of a human vein.What is the function of the part labelled X ?

Accepted Answer

. Part labelled X is vein valve or flap tissue. These perform the function of preventing flow of blood in backwards or downward direction.. When the blood has to reach the heart, it goes against the gravity. This is where valves come into function.. They are present in lower limbs.. Disorder of vein valve is condition named Chronic Venous Insufficiency (CVI).

Question 17

The diagram shows cross-sections through three types of blood vessel, not drawn to the same scale.Which section is from a vein and which is from a capillary?

Accepted Answer

V is an artery and has thick muscular walls which are elastic in nature.W is a vein which has thin muscular walls which are less elastic in nature.X is as Capillary. These tiny blood vessels have thin walls. Oxygen and nutrients from the blood can move through the walls and get into organs and tissues.

Question 18

The diagram shows one way the body defends itself against pathogens.What is the name of this defence mechanism?

Accepted Answer

The given diagram shows a defence mechanism known as phagocytosis. In phagocytosis the white blood cells surround, engulf, and destroy bacteria, foreign particles, and dying cells to protect the body. These WBCs are collectively referred to as phagocytes. Phagocytes eventually die.

Question 19

What is the approximate percentage of oxygen in expired air?

Accepted Answer

During exhalation, a mixture of gases is expired out that includes 16% oxygen, 4% carbon dioxide and 78% nitrogen. During Inhalation, the mixture of gases inhaled includes 21% oxygen, 0.04% carbon dioxide and 79% nitrogen.

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