Class 10 SELINA Solutions Biology Chapter 17 - Assertion-Reasoning Type Questions

Correct option: (c) A is True and R is False

Explanation: Different shapes of cells are often related to the different functions they perform. Human red blood cells (RBCs) are circular and biconcave, which allows them to easily pass through the blood capillaries and transport oxygen efficiently.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Nucleoli are one or more round-shaped sub-structures present inside the nucleus. They produce ribosomes and dictate them to synthesise proteins. Nucleolus participates in protein synthesis by forming and storing RNA.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Iodine solution makes the nucleus more visible by increasing the refractivity of light. Iodine is often used to stain the nucleus because it binds to the DNA within the nucleus. Iodine solution stains the nucleus more intensely than other cell structures, while also making the nucleoli darker.

So, the given assertion is true, but the reason is false.

Correct option: (b) Both A and R are False.

Explanation: Cell membrane is a very thin, flexible, living semi-permeable membrane. It regulates the entry of certain solutes and ions. It allows only certain substances to pass through it and restricts the entry of others.

So, both the assertion and reason are false.

Correct option: (d) A is False and R is True

Explanation: In plant cells, Golgi apparatus consists of several separate units called as dictyosomes while in animal cells it occurs as single compact or loose complex called as Golgi apparatus or Golgi complex. Plant cells have dictyosomes because the entire central space is occupied by a large, central vacuole which is used for osmotic control and nutrient storage.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: The basic structural unit of DNA is nucleotide. Each single DNA strand is composed of repeating nucleotides which are made of three components - phosphate group, pentose sugar arranged lengthwise and nitrogenous bases, adenine (A), guanine (G), cytosine (C) and thymine (T).

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Centromere is the point of attachment of two chromatids of a chromosome. Centrosome is found in animal cells only. It contains one or more centrioles. Centrosome initiates and regulates the process of cell division as it helps in the formation of spindle fibres with the help of asters.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Meiosis is the kind of cell division that produces the sex cells or the gametes. The most significant aspect of meiosis is that the number of chromosomes is halved in the gametes so that on fertilisation, the normal number of chromosomes (2n) is restored.

So, the given assertion is true, but the reason is false.

Correct option: (c) A is True and R is False

Explanation: Genetics is the study of heredity i.e., transmission of body features from parents to offspring. Thus, heredity is the basic fundamental unit of genetics. Genes are specific parts of a chromosome which determine the hereditary characteristics. They carry hereditary information from the parents to their offspring.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Karyokinesis is the division of nucleus during cell division. Karyotype is the number and appearance of the complete set of chromosomes in the nucleus of a eukaryotic cell. ‘Karyon’ means nucleus and ‘type’ explains the number, shape, and size of the chromosome.

So, the given assertion is false, but the reason is true.

(Disclaimer: Please note that the answer given in the textbook is option (c) - A is True and R is False, which is not correct)

Correct option: (b) Both A and R are False

Explanation: Dominant alleles can express themselves even in heterozygous condition. This kind of alleles express themselves regardless of the presence of another allele for a given gene. Recessive alleles can express themselves only in the homozygous condition i.e., in the presence of the same recessive allele. The expression of recessive allele is supressed in the presence of a dominant allele for a given gene.

So, both the assertion and reason are false.

(Disclaimer: Please note that the answer given in the textbook is option (a) - Both A and R are True, which is not correct)

Correct option: (c) A is True and R is False

Explanation: Genotype is the genetic makeup of a cell. It is the set of genes present in the cells of an organism that expresses internal characters. Phenotype is the observable characteristics which are genetically controlled.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: If the egg (X) is fused by X-bearing sperm, the resulting combination is XX, i.e., female constitution and the child born is a female (daughter). Thus, a daughter (XX) receives one X chromosome from her mother and one X chromosome from her father. As a result, she resembles both, her mother, and her father.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Roots absorb water and mineral nutrients from the soil and conduct them into the stem for supply to the leaves, flowers, and fruits. Soil is the storehouse of all the essential minerals for photosynthesis that are absorbed by the plant through the roots of the plant by the process of active transport using energy from ATP.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Diffusion is the free movement of molecules of a substance (solute or solvent, gas, liquid) from the region of their higher concentration to the region of their lower concentration when the two are in a direct contact. Thus, diffusion occurs in all three states of matter: solids, liquids, and gases. The main condition which regulates the process of diffusion is the concentration gradient and not the state of matter. It always occurs from higher to lower concentration.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: Phloem is a kind of complex permanent tissue in plants which surrounds the xylem tissue. It is present all throughout the plant – root, stem, or leaves. Translocation by phloem is bidirectional. The phloem transports food in upward as well as downward directions, depending on the plant's needs. For example, in early spring, sugar is transported from the root to the growing buds. In summer, sugar is transported from the photosynthesizing leaves to the roots.

So, the given assertion is false, but the reason is true.

Correct option: (a) Both A and R are True

Explanation: Active transport is the passage of substances such as salts or ions from their lower concentration to higher concentration through a living cell membrane. Cellular energy in the form of ATP is required for this kind of transport. Since diffusion occurs from a region of higher concentration to lower concentration, the direction of active transport is in a direction opposite to that of diffusion.

So, both the assertion and reason are true.

Correct option: (c) A is True and R is False

Explanation: Lenticels are special openings found on the surface of older woody stems. These allow for diffusion of gases for respiration. Lenticels never close. They remain open all the time.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Plants give out large quantities of water during transpiration. Thus, transpiration increases the amount of moisture in the atmosphere. Forests contribute in bringing rain because of transpiration.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Nerium is a xerophyte, which has adapted to thrive in environments with little or no water, including deserts. It has evolved a variety of permanent adaptations to curtail transpiration. Nerium leaves are narrower to reduce the surface area. The leaves have sunken stomata covered by trichomes to reduce the excessive loss of water through transpiration.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Transpiration helps in the ascent of sap by producing a suction force acting from the bottom of the plant. Transpiration is the evaporative loss of water through the aerial parts (leaves, stems) of a plant. The evaporation of water from the cells on the surface of the leaves creates a vacuum space, which is called transpiration pull. This pull pulls water from the cells at lower levels, concentrating the cell sap and increasing their osmotic pressure. The water then moves from the cells at lower levels in a sequential manner, which favours absorption of water from the soil by the roots.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: Photosynthesis primarily takes place in the leaves of a green plant. Chlorophyll is the green pigment found in the chloroplasts of a plant. It traps solar energy and converts it into chemical energy in the form of glucose.

So, the given assertion is false, but the reason is true.

Correct option: (a) Both A and R are True

Explanation: Guard cells regulate the opening and closing of the stomatal aperture. The movement of water in and out of the guard cells controls the opening and closing of stomata. Stomata are minute openings occurring in large numbers on the lower surface of a leaf. Guard cells are bean-shaped cells that contain chloroplasts, which allows them to make food through photosynthesis. They are the only epidermal cells that can make sugar.

So, both the assertion and reason are true.

Correct option: (d) A is False and R is True

Explanation: The mesophyll tissue is made up of two types of parenchymatous cells called spongy and palisade parenchyma. The palisade parenchyma is present on the upper side whereas the spongy parenchyma is placed on the lower side of the epidermis. The cells in the palisade parenchyma are elongated and are placed parallel to each other and arranged vertically whereas the cells in the spongy parenchyma are loosely arranged and are oval or round. The palisade layer is responsible for photosynthesis because it contains most of the chloroplasts in the leaf.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: Phosphorylation is the process in which electrons are used to convert ADP into energy-rich compound ATP by adding one phosphate group (iP). Since the energy used in the process comes from light, the process is termed as photophosphorylation. It is a light-dependent reaction. Photophosphorylation is a process that occurs during photosynthesis, not respiration.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Plants do not have a well-developed nervous system or sense organs to respond to the stimuli in the environment. Their sensitivity and coordination are the result of chemical control. Plants respond to stimuli by producing chemical compounds called hormones that work as messengers.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Parthenocarpic fruits are seedless, and the seeds that are present are usually small. Parthenocarpy is the process of fruit development without fertilisation, which can happen naturally or be induced. The fruit is sterile and lacks seeds and is also known as virgin fruit.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: Abscisic acid is a growth-retarding plant hormone. Auxins are powerful growth-stimulants. They are mainly synthesised in shoot apical meristems and young leaves.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Ethylene is the only hormone which is a gas at ordinary temperature. It helps in the ripening of fruits. It is produced in fruits and remains in the same fruit, i.e., its site of synthesis and site of action are not different.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Human beings have a closed blood vascular system in which blood in our body circulates in a closed manner i.e., all the time through the blood vessels. Blood is contained in the heart and openly flows all throughout the body via three kinds of blood vessels – arteries, veins, and capillaries. In animals such as insects, the blood mostly flows through open spaces in the body. Their blood flows from the heart to body spaces without vessels. Such a type of blood circulation is called an open blood circulatory system.

So, the given assertion is false, but the reason is true.

Correct option: (a) Both A and R are True

Explanation: The ventricles have thick muscular wall as compared to atria. This is because they must pump blood to long distances. The right ventricle pumps blood only up to the lungs for oxygenation. However, the left ventricle pumps blood up to the farthest points in the body, such as up to the toes in the feet or up to the brain against gravity. The left ventricle must generate enough force to pump oxygenated blood to the entire body, so it has thicker muscular walls compared to the right ventricle.

So, both the assertion and reason are true.

Correct option: (d) A is False and R is True

Explanation: Haemoglobin (Hb) is a respiratory pigment richly found in erythrocytes. It is formed of an iron-containing part called haemin and a protein called globin. Haemoglobin has the ability to combine readily with oxygen to form oxyhaemoglobin which delivers oxygen to the tissues and the cells.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Lymphocytes are a type of non-granular WBCs. Their cytoplasm does not have granules. Lymphocytes are the smallest of WBCs with a single large nucleus. They produce antibodies. The cytoplasm of granular WBCs such as basophils contains granules. Basophils release histamine for inflammation which dilates blood vessels.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: During blood coagulation, the injured tissue cells and the platelets which disintegrate at the site of wound release a substance called thrombokinase. The thrombokinase acts as an enzyme and with the help of calcium ions, converts prothrombin (inactive form) of the plasma into thrombin (active). Vitamin K, a fat-soluble vitamin, is essential to produce prothrombin.

Correct option: (c) A is True and R is False

Explanation: Blood group ‘AB’ does not contain any antibody but contains both the antigens ‘A’ and ‘B’. Hence, a person with blood group ‘AB’ can receive blood from all types i.e., ‘AB’, ‘A’, ‘B’ and ‘O’ is therefore, called universal recipient.

RBCs of human beings have specific proteins on their surfaces. These proteins are called antigens. The plasma of the blood contains complementary proteins called antibodies with respect to the antigen that is present on the surface of RBCs.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: The kidneys remove urea and water from the body during excretion in the form of urine. Sweat glands eliminate excess of water and sodium chloride along with small amounts of urea and lactic acid in the form of sweat. The human body produces wastes in the form of urea, uric acid, bile pigments, excess of carbon dioxide, water, and water vapour. Urea is highly poisonous, if allowed to accumulate in the blood to a certain level can cause death.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: The renal artery carries oxygenated blood and contains less nitrogenous waste. All arteries carry oxygenated blood, except for pulmonary artery. The pulmonary artery is the only artery that carries deoxygenated blood from the heart to the lungs to obtain oxygen.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: Afferent arterioles are larger in diameter than efferent arterioles. The difference in the size of the diameter of these arterioles creates a high pressure known as hydrostatic pressure. This high pressure causes the liquid part of the blood to filter out from the glomerulus into the renal tubule. This filtration under high pressure is called ultrafiltration.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Haematuria is the condition in which the blood passes with urine due to some infection in the urinary tract, kidney stones or tumour. Haemoglobinuria is the scientific term for the condition of having too much haemoglobin in the urine, which can be caused by excessive RBC destruction in the blood vessels. This releases haemoglobin into the plasma, which can cause haemoglobin to appear in the urine.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Effectors are muscles or glands which, on receiving the impulse from the brain or spinal cord, contract or secrete substances. Receptors are specialised epithelial cells of certain organs are capable of receiving stimuli which can be light (photoreceptors), sound (phonoreceptors), heat (thermoreceptors), pain (nociceptors), smell (olfactory receptors), etc. These receptors set up waves of impulses towards the central nervous system.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: Synapse is the point of contact between the terminal branches of the axon of a neuron with the dendrite of another neuron separated by a fine gap. The nerve impulse jumps into the next neuron at the synapse. Ganglia are the aggregates of the cytons or cell bodies of nerve cells from which the nerve fibres may arise or enter.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: The cerebrum is the largest portion of the brain. Cerebrum is the seat of intelligence, consciousness and will power. Cerebellum is a much smaller area of the brain located just at the base and under the cerebrum. It maintains body balance and coordinates muscular activity.

So, the given assertion is false, but the reason is true.

Correct option: (a) Both A and R are True

Explanation: Since the brain and the spinal cord are very delicate and sensitive organs of our body, they are protected by a three-layered membrane known as meninges. The outermost tough, fibrous membrane is duramater. The thin, delicate middle layer is the arachnoid. The inner, highly vascular membrane is the pia mater. The brain is well protected inside the brain box or the cranium of the skull. The spinal cord is protected by the vertebral column.

So, both the assertion and reason are true.

Correct option: (d) A is False and R is True

Explanation: The gray matter consists of cell bodies of the neuron, whereas the white matter contains the axons of the nerve cells. The arrangement of white and gray matter in the spinal cord is opposite to that in the brain. The gray matter lies on the outside (cortex) in the brain, but on the inside (medulla) in the spinal cord. The white matter lies on the inside (medulla) in the brain and outside (cortex) in the spinal cord.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: The sympathetic nervous system is stimulated by the hormone adrenaline secreted by the adrenal gland, located on the kidneys. Adrenaline is termed as emergency hormone because it is released by the adrenal glands under the conditions of stress or excitement. The sympathetic nervous system prepares the body for violent action against abnormal conditions.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Reflex action is an automatic, quick, immediate, involuntary action in the body brought about by a stimulus. Reflexes are involuntary but all involuntary actions are not reflexes. Reflexes of our body are controlled by the spinal cord while the involuntary actions are controlled by the medulla oblongata.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Lacrimal glands also called tear glands are located at the upper sideward portion of the eye orbit. 6 to 12 ducts of the gland pour the secretion in the form of tears over the front surface of the eye. Tears act as a lubricant and keep the eye surface clean. They have an antiseptic property due to the enzyme lysozyme which kills the germs.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: The choroid layer is richly supplied with blood vessels for providing nourishment to the eye. It contains a dark black pigment, melanin which prevents light rays from reflecting and scattering inside the eye. Choroid is the middle layer, sclerotic is the outer and retina is the inner layer of the eyeball. The retina contains rods and cones which contain the pigments rhodopsin and iodopsin respectively.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: The image formed on the retina is inverted and real. The light energy of the image produces chemical changes in the rods and cones. These changes generate nerve impulses which travel through the optic nerve and reach the visual area of the cerebrum, where they give the sensation of light. Our brain sees the objects upright even if the image formed in the eye is inverted. Both the eyes form two images, but the brain interprets them as one due to the overlapping of the images.

So, the given assertion is false, but the reason is true.

Correct option: (b) Both A and R are False

Explanation: Myopia is caused due to the lengthening of the eyeball from front to back or if the eye lens is too curved. Myopia can be corrected using suitable concave (diverging) lens which causes the light rays to diverge before they strike the lens of the eye. In myopia, the power of the glasses used is mentioned in minus “-”.

So, both assertion and reason are false.

(Disclaimer: Please note that the answer given in the textbook is option (d) - A is False and R is True, which is not correct)

Correct option: (d) A is False and R is True

Explanation: Semi-circular canals are present in the inner ear. One end of each of the three semi-circular canals is widened to form an ampulla which contains the sensory cells for dynamic balance while the body is in motion. The short stem joining the bases of the semi-circular canals to the cochlea shows utriculus and sacculus which contain sensory cells for statis balance when the body is stationary.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: The auditory canal transmits the air currents from the pinna to tympanum. The eustachian tube connects the cavity of the middle ear with the throat. It equalises the air pressure on either side of the ear drum allowing it to vibrate freely.

So, the given assertion is false, but the reason is true.

Correct option: (a) Both A and R are True

Explanation: The inner ear consists of cochlea, semi-circular canals, and the vestibule. One end of each of the three semi-circular canals is widened to form an ampulla which contains the sensory cells for dynamic balance while the body is in motion. The short stem joining the bases of the semi-circular canals to the cochlea shows utriculus and sacculus which contain sensory cells for statis balance when the body is stationary. Thus, the human ear is responsible for hearing, dynamic equilibrium, and static balance.

So, both assertion and reason are true.

Correct option: (c) A is True and R is False

Explanation: Hormones are the secretions from some glandular parts of the body which regulate certain physiological processes by chemical means. Hormones are directly poured into the blood. They act on target organs or cells of the same individual, usually away from their source, bringing about coordination between distant parts of the body.

So, the given assertion is true, but the reason is false.

Correct option: (b) Both A and R are False

Explanation: Adrenal medulla secretes adrenaline and nor-adrenaline. The adrenal cortex secretes mineralocorticoids and glucocorticoids. The glucocorticoids regulate carbohydrate, protein, and fat metabolism. Insulin regulates glucose levels of the blood. It stimulates the deposition of extra glucose in blood as glycogen in the liver and muscles. The roles of insulin and glucocorticoids are very different.

So, both the assertion and reason are false.

Correct option: (d) A is False and R is True

Explanation: Oversecretion of insulin causes hypoglycemia or insulin shock. Insufficient secretion of insulin causes hyperglycemia or diabetes mellitus. Oversecretion of insulin can lead to hypoglycemia by causing excessive uptake of glucose from the blood into the cells, which in turn can lead to increased insulin resistance and ultimately result in hyperglycemia or diabetes mellitus.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: Insufficient secretion of thyroxine or hypothyroidism causes cretinism in children. Cretinism is a condition which affects the growth of the children causing dwarfism and mental retardation. This disease occurs due to the defective development, or early atrophy (degeneration), of the thyroid.

So, the given assertion is false, but the reason is true.

Correct option: (a) Both A and R are True

Explanation: Placenta is a disc-like structure attached to the uterine wall. It develops from the fusion of the zygote and the endometrial lining, forming a specialised tissue structure that facilitates the exchange of substances between the maternal and foetal bloodstreams. The placenta is a vital organ during pregnancy, responsible for providing nutrients and oxygen to the developing foetus.

So, both the assertion and reason are true.

Correct option: (d) A is False and R is True

Explanation: Leydig cells are also called as interstitial cells, which are located as packing tissues between the coils of seminiferous tubules. These cells produce the male sex hormone testosterone. The ovaries in females secrete the female sex hormones, oestrogen, and progesterone.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Prostate gland is a bilobed structure which surrounds the urethra close to its origin from the bladder. It pours an alkaline secretion into the semen as it passes through the urethra. It neutralises the acidic pH of the vagina. Seminal vesicles are a pair of lobulated glands located between the posterior surface of the urinary bladder and the rectum.

So, the given assertion is true, but the reason is false.

Correct option: (d) A is False and R is True

Explanation: Fertilisation of the ovum and sperm occurs in the oviduct or fallopian tube of the female reproductive system. The vas deferens or the sperm duct is a long, muscular tube that runs from the epididymis into the pelvic cavity, behind the bladder, and connects to the urethra through the ejaculatory duct. It carries sperms from the epididymis to the urethra of the male reproductive system.

So, the given assertion is false, but the reason is true.

Correct option: (d) A is False and R is True

Explanation: Darwin’s theory of natural selection or Darwinism is mainly based on “survival of the fittest”. Lamarck’s theory of inheritance of acquired characters is based on two principles – ‘use and disuse’ and ‘inheritance of acquired characters. The principle of use and disuse states that parts of the body that are used extensively, become larger and stronger while those that are not used, deteriorate. Lamarck explained this principle by taking the example of giraffe’s neck.

So, the given assertion is false, but the reason is true.

Correct option: (c) A is True and R is False

Explanation: Vermiform appendix is a narrow, worm-like tubular structure, projecting from the blind end of the caecum (a part of large intestine). It is a vestigial or functionless organ in humans. Vestigial organs are those organs those organs that have ceased to be of any use to the possessor. The analogous organ to the vermiform appendix in herbivorous mammals is quite helpful in digesting cellulose. But it is considered a vestigial organ in humans.

So, the given assertion is true, but the reason is false.

Correct option: (a) Both A and R are True

Explanation: Natural selection operates through the preservation of favourable variations that enhance an organism’s ability to survive and reproduce, leading the gradual adaptation of populations to their environments over time. As the environment changes, new advantages get selected in nature. After several generations, sufficient characters get altered which leads to speciation. Thus, the theory of natural selection, proposed by Charles Darwin, is a fundamental mechanism driving human evolution.

So, both the assertion and reason are true.

Correct option: (b) Both A and R are False

Explanation: Population density is the number of individuals per square kilometre (km²) at any given time. It can be used to measure how an organism responds to local conditions, and to track the size of a population in relation to its environment. Towns and larger cities have a greater population density than the rural areas.

So, both assertion and reason are false.

Correct option :(b) Both A and R are False

Explanation: Tubectomy is a permanent method of contraception for females in which the oviducts are cut and ligated with a nylon thread. Tubectomy closes the passage of the egg. The epididymis stores the sperms for some days during which they mature and become motile. The sperm duct, also known as vas deferens carries sperms from the epididymis to the urethra of the male reproductive system.

So, both assertion and reason are false.

Correct option: (d) A is False and R is True

Explanation: Resources which once finished can never be replaced are called non-renewable resources. The underground reserves of fossil fuels such as coal and petroleum are fast depleting. Once finished, these resources cannot be formed again during a lifetime. Hence, fossil fuels are non-renewable and conventional sources of energy. It is crucial that people look at other non-conventional sources of energy like solar energy, tidal energy, etc. for their use to save the depletion of fossil fuels and make them available for the future generations.

So, the given assertion is false, but the reason is true.

Correct option: (a) Both A and R are True

Explanation: Pests are the enemies of crops because they eat up and destroy plant parts and sometimes cause diseases. Pesticides are the chemical substances used in agriculture to destroy pests including insects, rodents, fungi, and unwanted plants (weeds). DDT is an example of a pesticide which is widely used all over India.

So, both the assertion and reason are true.

Correct option: (c) A is True and R is False

Explanation: Ozone (O₃) is an allotropic form of oxygen (O₂). Ozone layer is a sort of sunscreen present high up in the atmosphere which prevents the harmful ultra-violet rays (UV-B) of the sun from harming us. Certain gaseous compounds such as CFCs (chlorofluorocarbons) released from the refrigerators and aerosol sprayers rise into the atmosphere. There they break down into chlorine atoms which in turn breakdown ozone into oxygen (O₂) and O.

So, the given assertion is true, but the reason is false.

Correct option: (a) Both A and R are True

Explanation: Greenhouse gases such as methane, carbon dioxide, nitrous oxide and water vapour are mainly responsible for trapping the thermal radiations, this entrapment leads to an overall increase in the temperature of the earth. Oxides of nitrogen and sulphur, primarily released through industrial activities and combustion processes, amplify the greenhouse effect by enhancing the heat-trapping capacities of the atmosphere, leading to an increase in the average global temperatures. The greenhouse effect is intensified by the presence of nitrogen oxides and sulphur oxides in the atmosphere, intensifying the absorption of heat and contributing to global warming. 

So, both assertion and reason are true.