Class 9 SELINA Solutions Biology Chapter 20: Assertion-Reasoning Type Questions

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

Explanation: Ichthyology deals with the study of fishes while Pisciculture deals with the technique of growing fishes. Hence, although both these branches are related to fishes, they are considered as different branches of biology as they deal with different types of fishes.

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

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

Explanation: The study of the effects of radioactivity on living things is termed as Nuclear Biology. It is also known as Radiation Biology as radioactive rays emit from the nucleus of the elements.

So, both assertion and reason are true.

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

Explanation: Animals which give birth directly to their young ones are called viviparous animals. The term viviparous is normally used for mammals who give birth to young ones. However, platypus and echidna are the only mammals that are oviparous, meaning they reproduce by laying eggs.

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

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

Explanation: Pathology deals with the study of diseases of plants and animals. It helps in the detection of diseases of plants and animals. Pathological tests cover blood tests, and tests on urine, stools (faeces) and bodily tissues.

So, both assertion and reason are true.

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

Explanation: Phycology also called Algology is the study of algae while Mycology is the study of fungi. Therefore, Phycology and Mycology are different branches of Biology.

So, both assertion and reason are false.

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

Explanation: Golgi apparatus is considered as the ‘delivery system of the cell’ which is concerned with the secretions of the cells including enzymes, hormones, etc. and their packaging and transport to different sites within the cell. Ribosomes are considered as ‘factories’ for the synthesis of proteins.

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

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

Explanation: Leucoplasts are colourless plastids as they have no pigments. They store starch and are normally found in the non-photosynthetic parts of a plant.

So, both assertion and reason are true.

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

Explanation: Cisternae are the hollow, tubular structures found in the membranous walls of the Golgi complex. Cristae are the finger-like projections arising from the inner walls of mitochondria. These projections increase the surface area of the inner membrane and help in the production of ATP.

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

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

Explanation: Euglena is an example of a eukaryotic cell. It is a unicellular organism. Eukaryotes are organisms with a well-defined nucleus with a nuclear membrane. Prokaryotes do not have a well-defined nucleus.

So, both assertion and reason are false.

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

Explanation: Chromosomes are suspended in the nucleoplasm of each cell whether is a plant cell or an animal cell. They are composed of DNA threads. Chromosomes carry hereditary information or genes from parents to offspring.

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

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

Explanation: Lateral (or cambium) meristem is situated below the bark. It is responsible for the increase in the girth (diameter) of the stem. Apical or terminal meristem is located near the tips of the root and stem and also on the tips of axillary buds where growth occurs at a faster rate.

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

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

Explanation: Sclerenchyma is composed of long and narrow cells. These cells have very thick walls due to the deposition of lignin. Parenchyma stores food and provides temporary support to the parts of a plant.

So, both assertion and reason are false.

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

Explanation: Tracheids (xylem) are made up of elongated dead cells with large cavities without any contents. They provide mechanical support to the plant. Sieve tubes (phloem) help in the conduction of prepared food from the leaves to other parts of a plant.

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

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

Explanation: Lymph is a fluid connective tissue. It contains white blood cells but no red blood cells. Lymph is concerned with transportation and immunity.

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

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

Explanation: Cardiac muscles are striated, uninucleated and branched. Cells are relatively short and located in the muscles of the heart. Cardiac muscles can contract without outside stimulation and do not get tired easily.

So, both assertion and reason are true.

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

Explanation: A complete or perfect flower is one which contains all the four floral whorls - Calyx, Corolla, Androecium and Gynoecium. If one or more sets of floral whorls are missing, the flower is called incomplete or imperfect. Most angiospermic flowers are complete or perfect. However, some species produce imperfect flowers that have only female or male structures.

So, both assertion and reason are false.

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

Explanation: Dioecious plants bear unisexual flowers on different plants. They bear staminate (male) and pistillate (female) flowers on different plants.

So, both assertion and reason are false.

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

Explanation: The kind of androecium in which the stamens are united in one group by their filaments is termed as Monadelphous. Monadelphous stamens are found in china rose and cotton flowers. Diadelphous stamens are found in Pea flowers while Polyadelphous stamens are found in Bombax flowers.

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

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

Explanation: The most attractive, colourful part of a flower is corolla made of petals. Calyx is the whorl of sepals which protects the young flower bud. Calyx, when green, also performs photosynthesis.

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

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

Explanation: Calyx and corolla are considered as non-essential (or accessory) parts of a flower because they do not directly participate in the process of reproduction. They are simply the helping parts which either protect the reproductive parts of the flower or make the flower attractive for pollination. Corolla attracts insects for pollination which is the first step of reproduction.

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

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

Explanation: Self-pollination is the transfer of pollen from the anther to the stigma of the same flower (autogamy) or to the stigma of another flower of the same plant (geitonogamy). Thus, autogamy and geitonogamy are the two kinds of self-pollination. Allogamy also called cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower of a different plant of the same species.

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

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

Explanation: Herkogamous flowers favour cross-pollination as these flowers have a structural or a mechanical barrier between the male and female reproductive parts. This arrangement ensures that the pollen of a flower does not reach the stigma of the same flower. Pansy is an example of a herkogamous flower. A hood covering the stigma acts as a mechanical barrier in flowers of Pansy.

So, both assertion and reason are true.

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

Explanation: The pollinating agents of entomophilous flowers are insects. These flowers are large and usually brightly coloured to attract insects for pollination.

So, both assertion and reason are false.

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

Explanation: During fertilisation, one sperm nucleus fuses with the egg cell nucleus to form the zygote. The other sperm nucleus moves towards the two polar nuclei in the central cell of the embryo sac and fuses with them to produce the endosperm nucleus. This process is termed as ‘triple fusion.’ Since two fertilisations occur, the entire event is called ‘double fertilisation.’

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

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

Explanation: Emasculation is a technique used by plant breeders to produce a desired plant variety through artificial pollination. It involves removing the anthers from a bisexual flower before it opens to prevent self-pollination and ensure cross-pollination with desired pollen grains.

So, both assertion and reason are true.

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

Explanation: Fruit is the enlarged ripened ovary which encloses the seeds. The ovarian wall forms the fruit wall or pericarp. Fruits develop from the ovary of the pistil after the process of pollination and fertilisation. Fruits protects the seeds and help in seed dispersal.

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

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

Explanation: Dicotyledonous seeds can either be albuminous (endospermic), e.g., poppy, or exalbuminous (non-endospermic), e.g., gram. All dicotyledonous seeds contain two cotyledons which store food material for the developing embryo.

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

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

Explanation: Micropyle is the opening through which the pollen tube enters the ovule. It helps in the diffusion of respiratory gases for the growing embryo. The seeds absorb water mainly through the micropyle and make it available to the embryo for germination.

So, both the assertion and reason are true.

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

Explanation: The single cotyledon of maize grain is termed as scutellum which does not store any food material for the developing embryo. In monocot seeds, like maize, the hilum and micropyle usually fuse together and become integrated into the seed coat, making them not visibly distinct.

So, both assertion and reason are false.

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

Explanation: In hypogeal germination, the epicotyl elongates faster, and the cotyledons remain underground. In epigeal germination, the hypocotyl elongates faster, and the cotyledons are pushed above the ground.

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

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

Explanation: Plants respire, or breathe, all the time, day, and night. They perform photosynthesis only during the daytime when stomata remain open and allow for gas exchange. All parts of the plant respire, including the leaves, stems, and roots. The leaves have stomata, which are tiny pores that allow for the exchange of gases. The stems have lenticels, which are small pores that also allow for the exchange of gases. The roots exchange gases through root hairs.

So, both assertion and reason are false.

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

Explanation: Respiration in a catabolic process which releases energy in the form of ATP. Respiration is a destructive or breakdown process which occurs in a series of chemical steps and produces ATP.

So, both assertion and reason are false.

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

Explanation: End products of anaerobic respiration in plants are ethyl alcohol and carbon dioxide. Incomplete breakdown of glucose occurs in the anaerobic respiration of plants.

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

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

Explanation: In many respects, respiration and photosynthesis in plants are distinctly opposite processes. The requirements of one are the products of the other and therefore, they are complementary to each other. In photosynthesis, food is manufactured, whereas in respiration, food is oxidised.

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

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

Explanation: Glycolysis and Krebs cycle are the two steps of respiration. Glycolysis occurs in the cytoplasm whereas Krebs cycle occurs in the mitochondria of a cell and releases energy.

So, both assertion and reason are false.

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

Explanation: Lenticels are small, lens-shaped openings found on the surface of the stem. They help in the diffusion of gases.

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

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

Explanation: Both Monera and Protista are similar with respect to their number of cells. They are single-celled or unicellular organisms. However, they differ with respect to their nuclei. Monerans have no organised nucleus and so, they are prokaryotic. Protists have a well-defined nucleus with a nuclear membrane and so, they are eukaryotic.

So, both assertion and reason are true.

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

Explanation: Gymnosperms are non-flowering plants which bear naked seeds, i.e., the seeds are not enclosed in fruits. They bear seeds in structures called cones. They bear both male and female cones containing pollen and ovules respectively.

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

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

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

Explanation: Jungle crow is different from the house crow with respect to features such as size, colour, and beak. They are two different species and hence, they cannot interbreed. All individuals of the same species can normally interbreed among themselves. Hence, although both jungle crow and house crow belong to the same genus Corvus, they cannot interbreed.

So, both assertion and reason are false.

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

Explanation: Ostia are the pores or openings in the body wall of sponges through which water enters inside the body. Osculum is a mouth-like structure on the top of the sponge’s body through which water is thrown out.

So, both assertion and reason are true.

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

Explanation: Clitellum is a short cylindrical band of thick glandular skin which surrounds the body of an earthworm like a belt in the segments 14-16 which is about one-third distance of the body from the front (anterior) end. Clitellum serves in reproduction.

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

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

Explanation: Pisces have a two-chambered heart while Amphibians have a three-chambered heart. As Pisces are the most primitive chordate, they have a two-chambered heart. Amphibians are little advanced than Pisces, so they have a three-chambered heart.

So, both assertion and reason are false.

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

Explanation: Bacteria are the smallest living organisms on the earth. Each bacterial cell contains a single chromosome which is not enclosed in a nuclear membrane. They are prokaryotes that lack a true nucleus.

So, both assertion and reason are false.

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

Explanation: Bacteria can be either saprotrophic or parasitic. Saprotrophic bacteria draw their nourishment from decaying dead organisms. Parasitic bacteria draw their nourishment from the body of their living hosts.

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

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

Explanation: Rhizobium is a type of bacteria found in the root nodules of leguminous plants. It converts free nitrogen from the soil and atmosphere into soluble nitrates. Clostridium is a free-living bacterium in the soil which converts soil nitrates into ammonia which in turn gets converted into amino acid and nitrates, enriching the soil.

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

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

Explanation: Fungi are non-chlorophyllous, saprotrophic plants which can be unicellular or multicellular. They do not contain chlorophyll and the mode of nutrition in them is heterotrophic instead of autotrophic.

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

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

Explanation: Pasteurisation is a technique of partial sterilisation applied usually to milk. It does not completely sterilise milk. Pasteurisation kills a majority of the bacteria usually present in milk, including the disease-causing bacteria.

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

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

Explanation: Both black rot of mustard and black rot of cauliflower are bacterial diseases.

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

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

Explanation: Polysaccharides are complex carbohydrates made up of multiple sugar molecules. Digestible polysaccharides, like starch, are made up of long chains of glucose molecules that can be broken down by digestive enzymes. Non-digestible polysaccharides, like cellulose have a different chemical structure that makes them resistant to digestion by human enzymes. The undigested cellulose, being fibrous in nature, acts as roughage and helps in digestion. Glycogen is also a polysaccharide. However, it does not provide roughage. It is the form in which carbohydrates are stored in animals.

So, both assertion and reason are false.

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

Explanation: Iodine is required for the proper functioning of the thyroid gland. It is the component of thyroxine hormone secreted by the thyroid gland. Deficiency of iodine in the diet leads to goitre.

So, both assertion and reason are 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: Haemoglobin is a respiratory pigment consisting of iron and globin protein. The deficiency of iron causes anaemia because it is required for the formation of haemoglobin.

So, both assertion and reason are false.

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

Explanation: Diet is the combination of food items which we eat in our meals every day. A diet must contain all the food components in the required amount for a particular person. Such a diet is called a balanced diet.

So, both assertion and reason are true.

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

Explanation: Both galactose and lactose are sugars present in milk and soluble in water. Galactose is a monosaccharide or a simple sugar which gets absorbed into the body without digestion. Lactose is a disaccharide or a double sugar which requires digestion to get absorbed into the body.

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

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

Explanation: Both Kwashiorkor and marasmus are protein deficiency diseases usually affecting children. Kwashiorkor is a severe protein deficiency disease usually affecting young children. Marasmus is caused due to the deficiency of carbohydrates, fats and proteins and usually affects infants below the age of one year.

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

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

Explanation: The last molar of each side in each jaw is called wisdom tooth. The wisdom teeth are so called because they appear at an age of about 17-20 years when the human body is reaching maturity. The wisdom teeth are not responsible for the intelligence of a person

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

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

Explanation: Dentine forms the bulk of the tooth. It has minute canals through which run the strands of cytoplasm of the cells in pulp cavity. Cement is a bone-like structure which covers and fixes the root of a tooth in position.

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

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

Explanation: Ptyalin is salivary amylase present in the saliva secreted by the salivary glands. Amylopsin is pancreatic amylase present in the pancreatic juice secreted by the pancreas. Both ptyalin and amylopsin are the same with respect to their enzymatic activity. Both enzymes convert starch into maltose.

So, both assertion and reason are true.

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

Explanation: Pylorus is the structure which prevents the entry of food from the stomach to the intestine. Pylorus has a ring of muscles to keep the opening of the stomach closed like a valve. It is located at the back end of the stomach where it meets the small intestine.

So, both assertion and reason are false.

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

Explanation: Bile juice is produced in the liver and is stored temporarily in the gall bladder. Bile juice is poured in duodenum through the common bile duct. It converts the acidic pH of the food received from the stomach and makes it alkaline and enables the pancreatic and intestinal enzymes to act.

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

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

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

Explanation: The small intestine is about 7 metres long while the long intestine is about 1.5 metres long. Hence, the length of the small intestine is greater than the large intestine. The small intestine is a long, narrow, and highly coiled tube that folds many times to fit inside the lower abdominal cavity. It increases the surface area for the absorption of nutrients.

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

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

Explanation: Axial skeleton includes the skull, the vertebral column, the ribs, and the sternum. It lies in the central axis of the human body. The appendicular skeleton includes the bones of the limbs and girdles of the human body.

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

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

Explanation: Each hip bone is made up of three fused bones – ilium, ischium, and pubis. The hip bone is technically termed as pelvis. It is wider and trough-shaped in females to adapt for accommodating the foetus in the uterus during pregnancy.

So, both assertion and reason are 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: (c) A is True and R is False

Explanation: The freely movable joints like the shoulder joint and knee joint are synovial joints. Synovial fluid is present in the synovial joints which provides lubrication to the bones and removes friction. Immovable joint is found between the bones of cranium.

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

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

Explanation: Gliding joint occurs between the bones of the wrist. In this type of joint, varying degrees of movement are possible between the two bones forming the joint. Ball and socket joint is found in shoulders. This joint provides movement in any direction.

So, both assertion and reason are false.

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

Explanation: Radius and ulna are the two long bones of the lower arm. Tibia and fibula are the two long bones of the shank.

So, both assertion and reason are true.

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

Explanation: Sternum or the breastbone is a long, flat bone lying in the middle of the front part of the chest. Sacrum is a large bone formed by the fusion of five vertebrae. It is found between the lumbar vertebrae and coccyx.

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

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

Explanation: Adipose cells are located in the lowest part of the dermis. This subcutaneous fat stores reserve food in the form of protein which can be used during starvation. It also acts as a heat-insulating layer as well as a shock absorber.

So, both assertion and reason are true.

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

Explanation: Keratin is the fibrous structural protein located in the stratum corneum of the epidermis. It makes the skin tough and impervious.

So, both assertion and reason are true.

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

Explanation: Leather obtained from the hides of animals is the dermis of the skin. Dermis is tough and flexible which is made up of a thick layer of connective tissue with elastic fibres.

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

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

Explanation: Skin is the largest sense organ, which is concerned with the sensation of pressure, pain, heat and cold. Skin is the main organ of integumentary system concerned with the protection of the body against mechanical, thermal and physical injury, and perspiration.

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

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

Explanation: Vasodilation is the phenomenon in which the blood vessels become wider and supply more amount of blood to the skin. Vasoconstriction normally occurs during cold climatic conditions or when a person becomes nervous or stressed.

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

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

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

Explanation: The product of combination of carbon dioxide and haemoglobin is termed as carbamino-haemoglobin. RBCs carry carbamino-haemoglobin from the tissue cells to blood capillaries. Hence, carbon dioxide gas is exhaled out.

So, both assertion and reason are false.

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

Explanation: The entrance to the trachea is guarded by a flap called epiglottis which closes at the time of swallowing food. Incomplete closure of epiglottis during swallowing causes cough.

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

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

Explanation: Pulmonary artery carries deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation. The pulmonary veins carry oxygenated blood from the lungs to the left auricle of the heart.

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

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

Explanation: Diaphragm contracts and flattens downwards during inspiration. This increases the volume of chest cavity and decreases pressure. Decreased pressure inside the lungs draws air inwards. Diaphragm relaxes and moves upwards to a dome shape during expiration. This decreases the volume of chest cavity. The lungs are compressed, forcing air out into the atmosphere.

So, both assertion and reason are true.

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

Explanation: Asphyxiation is a condition in which the blood becomes more venous by the accumulation of more carbon dioxide because of which the oxygen supply is diminished. Hypoxia is the deficiency of oxygen reaching the tissues. Asphyxiation and hypoxia both are different with respect to the amounts of carbon dioxide and oxygen respectively.

So, both assertion and reason are true.

(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: Malaria is caused by a protozoan, Plasmodium which is spread by Anopheles mosquito. There are two hosts in the life cycle of a malarial parasite which are Anopheles mosquito and humans/monkeys/birds, etc.

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

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

Explanation: Gambusia is a kind of fish which should be introduced in ponds. These fishes enhance the oxygen content of the water. Gambusia fishes selectively devour mosquito larvae from the ponds. Hence, they are used to control the growth of mosquitoes.

So, both assertion and reason are true.

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

Explanation: Bacillary dysentery is caused due to infection by a bacterium. It occurs frequently in children. Shigella is a kind of bacillus bacteria which causes bacillary dysentery.

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

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

Explanation: Hygiene is defined as the science and practice of maintaining good health. It requires caring of one’s own body (personal hygiene) and taking proper care of surroundings (social hygiene).

So, the given assertion is true, but the reason is 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: When the disease is widely distributed worldwide, it is termed as a pandemic disease. COVID-19 and AIDS are pandemic diseases. Sporadic diseases such as malaria and cholera are not localised, their individual cases are scattered.

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

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

Explanation: Goitre is a kind of a nutritional deficiency disease as well as metabolic disease. Goitre is caused due to the deficiency of iodine in the diet. Iodine is required for the synthesis of thyroxine by thyroid gland.

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

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

Explanation: The disease-causing germs are called pathogens. The transmission of germs from one person to another is carried out by certain organisms which are termed as vectors.

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

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

Explanation: Taeniasis is the disease caused by tapeworms called Taenia solium. It spreads by eating infected pork or beef. Pigs or cows accidentally ingest the eggs of tapeworm which later on form larval stages. These larvae settle in the muscles of pigs or cows. When man eats raw or imperfectly cooked pork or beef, the worm matures in his intestine, and he gets infected by taeniasis.

So, both assertion and reason are true.

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

Explanation: The viruses are extremely small substances made of nucleic acids (RNA) and proteins. Viruses are considered as a connecting link between the living and non-living beings as they can multiply and be crystallised and stored for years.

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

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

Explanation: Immunity is the body’s defence against diseases. It is the resistance to the onset of a disease after infection by harmful germs. The body fluids contain special proteins called antibodies which react with the invading germs and antitoxins which react with their poisons to destroy them and thus, provide protection against the diseases.

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

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

Explanation: Antibodies are produced by a type of specialised lymphocytes on exposure to antigens. An antibody recognises its particular antigen and binds to it rendering it harmless, which is subsequently destroyed and eliminated by the body. Thus, antibodies protect us from disease-causing germs.

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

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

Explanation: The vaccine for tuberculosis is made up of living, weakened germs. The freeze-dried BCG vaccine containing living, weakened germs was satisfactory to prevent the tuberculosis disease.

So, both assertion and reason are false.

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

Explanation: Active immunity is produced by one’s own body. Active immunity is induced by infection (naturally acquired active immunity) or by contact with immunogens (artificially acquired active immunity).

So, both assertion and reason are true.

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

Explanation: Both antiseptics and disinfectants are used to kill germs which can cause several diseases. Antiseptics are mild chemical substances which, when applied on the body, kill germs. Disinfectants are strong chemical substances that are applied on spots and places where germs thrive and multiply.

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

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

Explanation: Untreated sewage or effluents from industries poured into rivers harm the people living nearby the rivers. Sewage becomes a suitable medium for microbes and insects to flourish which can cause many waterborne diseases such as diarrhoea, typhoid, and dysentery.

So, both assertion and reason are true.

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

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

Explanation: Red Cross is a national as well as an international agency. Its key role is to extend relief and help to the victims of any calamity – flood, fire, famine, etc. The emblem of Red Cross Society is a red coloured cross painted on a white background.

So, the given assertion is true, but the reason is 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: (b) Both A and R are False

Explanation: Red Cross Society was formally founded in 1864 and World Health Organisation (WHO) was established in 1948. Therefore, Red Cross is an older international body than WHO.

So, both assertion and reason are false.

(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: (a) Both A and R are True

Explanation: Waste is any substance which is discarded after primary use, or is worthless, defective and of no use.

So, both assertion and reason are true.

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

Explanation: Clothes that are old and torn, old bedsheets, blankets and cushions are termed as rags. Rags are a kind of domestic waste. Municipal waste includes household discharge of excreta, kitchen washings, discharge from public toilets, hospitals, hotels, etc.

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

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

Explanation: Incineration is the disposal of waste by burning. Incineration is harmful as it releases fumes and harmful substances.

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

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

Explanation: Electronic waste consists of discarded appliances using electricity such as old computers, mobile phones, batteries, fluorescent tubes, radios, etc. It may contain harmful substances such as lead, cadmium, and mercury. It may also contain some valuable reusable materials such as gold, silver, and copper.

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

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

Explanation: Electrostatic precipitators remove particulate air pollutants by attracting them to electrically charged plates. The electrostatic precipitators can remove upto 90% of particulate matter from thermal plants. Scrubbers are devices used to remove gaseous as well as particulate air pollutants.

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