Structural Organisation in Animals MCQ

Correct Answer: B. All functions are carried out by a single cell. In unicellular organisms, a single cell is responsible for all life processes.

Correct Answer: B. Tissues. Tissues are groups of similar cells organized to perform a specific function.

Correct Answer: C. To coordinate functions of organs. Organ systems consist of multiple organs working together to perform major bodily functions.

Correct Answer: C. To increase efficiency and survival. Division of labour allows specialized cells, tissues, and organs to perform specific tasks efficiently, enhancing the organism’s overall survival.

Correct Answer: B. Molecules. While organisms are made of molecules, molecules themselves are not considered a level of biological organization in the hierarchy of cells, tissues, organs, and organ systems.

Correct Answer: C. Epithelial. Epithelial tissue covers body surfaces, lines body cavities, and forms glands.

Correct Answer: B. Connecting and supporting other tissues. Connective tissue provides structural support, binds tissues together, and includes types like bone, cartilage, and blood.

Correct Answer: C. Muscular. Muscular tissue is composed of cells that can contract, generating force and producing movement.

Correct Answer: B. It transmits electrical impulses. Neural tissue, comprising neurons and glial cells, is specialized for communication through electrical and chemical signals.

Correct Answer: C. Connective, muscular, neural, and epithelial. The heart is a complex organ composed of all four basic tissue types working together.

Correct Answer: D. Neural. Neural tissue is specialized for conducting electrical signals (nerve impulses) throughout the body.

Correct Answer: A. Covering organs and body surfaces. Epithelial tissue forms the outer layer of the skin, lines internal organs, and cavities.

Correct Answer: D. Connective. Connective tissue includes bone, cartilage, tendons, ligaments, and blood, all providing support or connection.

Correct Answer: B. Muscular. Muscle tissue contracts to cause movement of body parts or substances within the body.

Correct Answer: C. Nervous system. The nervous system, including the brain, spinal cord, and nerves, is composed mainly of neural tissue.

Correct Answer: C. Digestive system. An organ system is a group of organs (like the stomach, intestines, liver) working together, such as the digestive system.

Correct Answer: D. Kidney. The kidneys are the primary organs of the excretory system responsible for filtering waste products from the blood and producing urine.

Correct Answer: D. Four. Most complex organs, like the heart or stomach, are composed of combinations of the four basic tissue types: epithelial, connective, muscular, and neural.

Correct Answer: B. Kidney. The kidney is part of the excretory system, while the lungs, bronchi, and trachea are components of the respiratory system.

Correct Answer: C. It increases with evolution. Generally, as animals evolved, their organ systems became more complex and specialized.

Correct Answer: B. Pumping blood. The heart is the central organ of the circulatory system, responsible for pumping blood throughout the body.

Correct Answer: C. Respiratory system. The lungs are the primary organs for gas exchange in the respiratory system of air-breathing vertebrates like frogs.

Correct Answer: B. Excretory system. The excretory system, including the kidneys, removes metabolic wastes from the body.

Correct Answer: B. Liver. The liver plays a crucial role in detoxification, metabolism, and producing bile for digestion.

Correct Answer: C. A group of organs working together for a common purpose. An organ system integrates the functions of several organs to perform complex tasks.

Correct Answer: B. Amphibia. Frogs are amphibians, characterized by their ability to live both in water (typically as larvae) and on land (as adults).

Correct Answer: B. Rana tigrina. Rana tigrina, the Indian bullfrog, is a common species found in India.

Correct Answer: B. They are cold-blooded and body temperature varies with the environment. Poikilothermic (cold-blooded) animals cannot regulate their internal body temperature, which fluctuates with the ambient temperature.

Correct Answer: D. Camouflage. Frogs use camouflage (also called protective coloration) to blend in with their surroundings and avoid predators.

Correct Answer: B. Summer and winter. Frogs undergo aestivation (summer sleep) during hot, dry periods and hibernation (winter sleep) during cold periods.

Correct Answer: C. Amphibian. Amphibians are vertebrates adapted to live both in aquatic and terrestrial environments.

Correct Answer: C. Summer. Aestivation is a state of dormancy that helps frogs survive hot and dry summer conditions.

Correct Answer: C. Camouflage. Camouflage allows frogs to blend with their environment, making them harder for predators to spot.

Correct Answer: B. Winter. Hibernation is a state of inactivity and metabolic depression during the cold winter months.

Correct Answer: C. Adaptability. Frogs exhibit various adaptations, such as camouflage, hibernation, and aestivation, allowing them to survive in diverse conditions.

Correct Answer: B. To assist in breathing and maintain moisture. The mucus keeps the frog’s skin moist, which is essential for cutaneous respiration (breathing through the skin) and prevents dehydration.

Correct Answer: A. Tail. Adult frogs lack a tail, although their larval stage (tadpole) possesses one.

Correct Answer: C. Five. Frogs typically have five webbed digits on their hind limbs, adapted for swimming and leaping.

Correct Answer: C. It protects the eyes while underwater. The nictitating membrane is a transparent third eyelid that covers and protects the eye when the frog is submerged, while still allowing vision.

Correct Answer: D. Digging. While forelimbs aid in walking, landing after leaps, and propping the body, they are generally not adapted for digging. Hind limbs are primarily used for leaping and swimming.

Correct Answer: B. Olive green with dark spots. The dorsal (back) side of Rana tigrina is typically olive green with irregular dark spots for camouflage.

Correct Answer: A. Tympanum. The tympanum is a visible eardrum located behind the eye, which receives sound vibrations.

Correct Answer: B. Presence of vocal sacs. Male frogs typically have vocal sacs (used for croaking) and nuptial pads on their forelimbs, which are absent in females.

Correct Answer: B. Swimming. The webbed skin between the digits of the hind limbs increases the surface area, providing propulsion for swimming.

Correct Answer: C. Tympanum. The tympanum (eardrum) vibrates when struck by sound waves, transmitting these vibrations to the inner ear.

Correct Answer: C. Intestine. Food passes from the stomach into the small intestine (duodenum, then ileum) for further digestion and absorption.

Correct Answer: C. Gall bladder. The liver produces bile, which aids in fat digestion, and it is stored in the gall bladder before being released into the intestine.

Correct Answer: C. Pancreas. The pancreas produces pancreatic juice containing digestive enzymes that break down carbohydrates, proteins, and fats.

Correct Answer: C. Intestine. The final stages of digestion and the primary absorption of nutrients occur in the small intestine.

Correct Answer: B. Chyme. Food mixed with gastric juices in the stomach forms a semi-liquid mixture called chyme, which then enters the intestine.

Correct Answer: B. Intestine. The inner walls of the intestine, particularly the small intestine with its villi and microvilli, are adapted for absorbing digested nutrients.

Correct Answer: B. It produces enzymes for digestion. The pancreas secretes digestive enzymes into the small intestine to break down food molecules.

Correct Answer: C. It emulsifies fats. Bile breaks large fat globules into smaller droplets (emulsification), increasing the surface area for enzymes to act upon.

Correct Answer: B. Skin. Frogs can absorb dissolved oxygen from water directly through their moist, permeable skin (cutaneous respiration).

Correct Answer: C. Pulmonary respiration. Respiration using the lungs is termed pulmonary respiration, common when frogs are on land or active.

Correct Answer: C. Through skin. During dormancy (aestivation or hibernation), metabolic rate is low, and cutaneous respiration through the skin is often sufficient.

Correct Answer: C. Nostrils. Air enters the frog’s respiratory system through the external nares (nostrils).

Correct Answer: B. Skin. Frogs absorb water directly through their permeable skin, particularly through a specialized region on their belly called the “pelvic patch.”

Correct Answer: A. Nostrils. Air is drawn into the buccal (mouth) cavity through the nostrils before being forced into the lungs.

Correct Answer: B. Three. The frog heart has three chambers: two atria (left and right) and one ventricle.

Correct Answer: C. Plasma, RBCs, WBCs, and platelets. Frog blood consists of plasma (liquid matrix) and formed elements including red blood cells (RBCs), white blood cells (WBCs), and platelets (thrombocytes).

Correct Answer: B. Carrying oxygen. Hemoglobin, located within red blood cells, binds to oxygen in the lungs and skin capillaries and transports it to the body tissues.

Correct Answer: C. Lymphatic system. The lymphatic system collects excess tissue fluid (lymph) and returns it to the bloodstream, and it also plays a role in the immune response.

Correct Answer: C. Hepatic portal vein. The hepatic portal system involves the hepatic portal vein carrying nutrient-rich blood from the intestine directly to the liver for processing.

Correct Answer: B. Left atrium. The left atrium receives oxygenated blood returning from the lungs and skin.

Correct Answer: C. Heart. The pericardium is a protective double-layered sac that encloses the heart.

Correct Answer: B. Closed. Frogs have a closed circulatory system, meaning blood is contained within vessels (arteries, veins, capillaries) throughout its circulation.

Correct Answer: B. Urea. Adult frogs primarily excrete urea, which is less toxic than ammonia and requires less water for excretion. Tadpoles excrete ammonia.

Correct Answer: A. Cloaca. The cloaca is a common chamber that receives waste from the digestive and excretory systems, as well as gametes from the reproductive system, before exiting the body.

Correct Answer: D. Urinary bladder. Urine produced by the kidneys travels down the ureters to the thin-walled urinary bladder for temporary storage before being expelled via the cloaca.

Correct Answer: C. Urinogenital ducts. In male frogs, the ureters carry both urine from the kidneys and sperm from the testes to the cloaca, hence they are called urinogenital ducts.

Correct Answer: C. Ureotelic. Organisms that primarily excrete urea as their nitrogenous waste are termed ureotelic. Adult frogs are ureotelic.

Correct Answer: C. Kidney. The kidneys are the primary organs responsible for filtering nitrogenous wastes and excess salts and water from the blood to produce urine.

Correct Answer: C. 10. Frogs possess 10 pairs of cranial nerves originating from the brain, controlling various sensory and motor functions.

Correct Answer: C. Cerebellum. The cerebellum, located in the hindbrain, is primarily responsible for coordinating muscular activity and maintaining balance.

Correct Answer: B. Cranium. The brain is enclosed and protected by the bony cranium, which is part of the skull.

Correct Answer: C. Autonomic nervous system. The autonomic nervous system regulates involuntary functions such as heart rate, digestion, and glandular secretions.

Correct Answer: B. Midbrain. The midbrain in frogs mainly consists of the optic lobes, which are involved in processing visual information.

Correct Answer: B. Coordinates reflex actions and transmits signals. The spinal cord serves as a pathway for nerve signals between the brain and the rest of the body and mediates reflex actions.

Correct Answer: B. Near the kidneys. The paired, yellowish testes are attached to the upper part of the kidneys by a fold of peritoneum called the mesorchium.

Correct Answer: B. Externally. The female releases eggs into the water, and the male releases sperm over them, resulting in external fertilization.

Correct Answer: C. 2500-3000. Female frogs lay a large mass of eggs, typically numbering between 2500 and 3000 at once.

Correct Answer: B. Vasa efferentia. Sperm travels from the testes through fine tubules called vasa efferentia, which enter the kidneys and connect to the urinogenital duct.

Correct Answer: C. Tadpole. Fertilized frog eggs develop into aquatic larvae known as tadpoles, which undergo metamorphosis to become adult frogs.

Correct Answer: C. Metamorphosis. Frogs exhibit metamorphosis, a significant transformation from the aquatic larval (tadpole) stage to the terrestrial/semi-aquatic adult stage.

Correct Answer: C. Insect control. Frogs are important predators of insects and other invertebrates, helping to control their populations.

Correct Answer: B. Food chain and food web. Frogs serve as both predators (eating insects) and prey (eaten by snakes, birds, etc.), playing a crucial role in the flow of energy through food chains and webs.

Correct Answer: B. Controlling pests. By consuming large numbers of insects, frogs help control agricultural pests, benefiting crop production.

Correct Answer: C. Muscular legs. The hind legs of some larger frog species are considered a delicacy in various cuisines.

Correct Answer: C. By serving as both predators and prey. Their position in the food web helps regulate populations of both invertebrates (their prey) and larger predators (which eat them), contributing to ecosystem stability.

Correct Answer: B. They are a food source. Frogs are an important part of the diet for many predators, including snakes, birds of prey, mammals, and larger fish.

Correct Answer: B. Habitat destruction. The loss and fragmentation of wetland and forest habitats due to human activities is a primary threat to frog populations worldwide.

Correct Answer: C. They control insect populations. As significant insectivores, frogs help keep insect numbers in check, which benefits ecosystems and agriculture.

Correct Answer: B. Tadpole. Tadpoles are aquatic herbivores or detritivores, playing a role in consuming algae and decaying matter in freshwater ecosystems.

Correct Answer: B. As models in studies of ecology and evolution. Frogs are used in research related to developmental biology, physiology, ecology, and environmental monitoring due to their sensitivity to environmental changes.

Correct Answer: B. Insects. Frogs are primarily insectivorous, consuming a wide variety of insects, including many considered pests.

Correct Answer: B. Water quality. Due to their permeable skin and reliance on aquatic environments for reproduction, frogs are sensitive to pollutants and changes in water quality, making them good bioindicators.

Correct Answer: C. Imbalance in food chains. Over-harvesting frogs for food can disrupt local ecosystems by removing a key predator of insects and a food source for other animals.

Correct Answer: C. Freshwater. Frogs are integral components of freshwater ecosystems like ponds, marshes, and streams, both as larvae and adults.

Correct Answer: B. Climate conditions. Changes in temperature and rainfall patterns associated with climate change significantly impact frog breeding, development, and habitat availability.