Biology

(d) it absorbs its food from general body surface

A tapeworm is an endoparasite living in the host intestine, which provides digested food. It absorbs this directly through its body surface (tegument), so it has no mouth or digestive system. Being a parasite or living in the intestine is not itself the reason.

(d) All of the above

Flatworms (Platyhelminthes) are acoelomate and have no circulatory, respiratory or skeletal system. Gas exchange occurs by diffusion across the body surface, and the flattened body keeps diffusion distances short.

(c) Pseudocoel

Ascaris is a pseudocoelomate. Its body cavity is not lined by mesoderm on both sides (no peritoneum), so it is a false coelom lying between the body wall and the alimentary canal.

(d) Arachnida

Spiders, scorpions and mites have a cephalothorax and abdomen, four pairs of legs and no antennae. Crustacea (two pairs), Myriapoda and Insecta (one pair) all bear antennae.

(a) Parasitism

The tough, non-living cuticle of Ascaris protects it from the host's digestive enzymes and immune attack, so it is an adaptation for the parasitic mode of life.

(a) Cockroach

Cockroach respires through a tracheal system that carries air directly to the tissues. Its haemolymph does not transport oxygen. In birds, rabbits and earthworms (haemoglobin in plasma) blood carries oxygen.

(c) They have developed respiratory organs

Insects have an efficient tracheal system that delivers oxygen directly to the cells, supporting the high metabolic rate needed for their activity and flight.

(a) Spread diseases

A vector is an organism, such as a mosquito or housefly, that carries and transmits disease-causing pathogens from one host to another.

(d) Sand fly

Kala-azar (visceral leishmaniasis) is caused by Leishmania donovani and transmitted by the female sand fly (Phlebotomus argentipes).

(b) Chrysalis

The pupa of a butterfly is called a chrysalis. The caterpillar is the larva, and the imago is the adult.

(d) As many pairs of legs as body segments except the last (and the first)

Centipedes (class Chilopoda) have one pair of legs on each trunk segment, so the number of leg pairs matches the segments, apart from the segments at the ends. The leg number varies with species, so (a) and (b) are not general.

(b) Filariasis

Filariasis is caused by the nematode Wuchereria bancrofti and spread by Culex mosquitoes. Amoebiasis is caused by a protozoan, while tuberculosis and leprosy are bacterial.

(a) Bilaterally symmetrical

All vertebrates can be divided into two equal halves along only one plane, so they show bilateral symmetry.

(d) Echinodermata

The water vascular system, a network of canals ending in tube feet, is a unique feature of echinoderms such as starfish. It is used for locomotion, feeding and respiration.

(a) Ichthyology

Ichthyology is the study of fishes. Herpetology deals with reptiles and amphibians, ornithology with birds, and mammalogy with mammals.

(d) Skin & gills

A frog tadpole breathes mainly with gills (external, then internal), and also through its skin. Lungs develop only after metamorphosis.

(d) Vipera

Among these, Vipera (viper) gives birth to young (ovoviviparous/viviparous). Bungarus, Naja naja and Natrix lay eggs.

(d) All of above

Snakes lack limbs and limb girdles (vestiges exist only in a few, such as pythons) and have no movable eyelids. Their eyes are covered by a transparent spectacle.

(d) They have 7 cervical vertebrae

Nearly all mammals, from the giraffe to the mouse, have seven neck vertebrae. Not all are viviparous (monotremes lay eggs), and diets vary.

(b) Feathers

Feathers are found only in birds and are their unique defining feature. Wings are shared with bats and insects, and a four-chambered heart is also present in mammals.

(c) Mollusca

Octopus is a cephalopod mollusc with a soft, unsegmented body, mantle and no external shell.

(b) Garden snail

Helix is the genus of the common garden snail, a terrestrial pulmonate mollusc. Apple snail is Pila.

(a) Annelids

In annelids such as earthworm the body is divided into segments (metameres), and the anus opens at the last segment, the pygidium.

(a) Carpals

The wrist has eight small carpal bones. Metacarpals form the palm, the humerus is the upper arm, and tarsals are in the ankle.

(a) Rabbit

Rabbit is a mammal and is warm-blooded (homeothermic), keeping a constant body temperature. Turtle, frog and fish are cold-blooded.

(d) Ichthyology

Ichthyology is the branch of zoology dealing with fishes. Saurology concerns lizards, and herpetology reptiles and amphibians.

(a) Major ecological groupings of animals and plants

A biome is a large regional community of plants and animals shaped by climate, such as tundra, taiga, grassland, desert and tropical rainforest. It groups both plants and animals, so (b) and (c) are too narrow.

(d) Fossils

Paleontology is the study of fossils, which are the preserved remains or impressions of ancient organisms. It is used to reconstruct the history of life.

(b) Ethology

Ethology is the branch of zoology that studies animal behaviour, mainly in natural conditions. Ecology deals with organisms and their environment, and ichthyology with fishes.

(a) Ronald Ross

Ronald Ross showed in 1897 that the Anopheles mosquito transmits the malarial parasite. Laveran had earlier discovered the parasite itself in 1880.

(c) Fish

Piscivorous (piscivore) animals are fish-eaters, from Latin piscis, meaning fish.

(b) Wallace

Alfred Russel Wallace independently arrived at the theory of natural selection. His 1858 paper was presented together with Darwin's at the Linnean Society.

(c) Cerebrum

The cerebrum is the seat of intelligence, memory, learning and conscious thought. The cerebellum controls balance and coordination, the hypothalamus regulates homeostasis, and the medulla controls vital reflexes.

(d) 12 pairs

Humans have 12 pairs of cranial nerves arising from the brain, from olfactory (I) to hypoglossal (XII).

(a) Brain

The human brain contains about 86 billion neurons plus a comparable or larger number of glial cells, far more cells than the spinal cord, retina or tongue.

(b) Ecology

Ecology is the study of the interactions between living organisms and their environment. An ecosystem is the functional unit itself, not the study of it.

(c) 31 pairs

Humans have 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal.

(d) Pituitary

Growth hormone (somatotropin) is secreted by the anterior lobe of the pituitary gland. It promotes growth of bones and tissues.

(d) All of these

The pancreas is both an endocrine and an exocrine gland. Its islets of Langerhans secrete insulin (beta cells) and glucagon (alpha cells), and it also secretes digestive enzymes into pancreatic juice.

(a) Frog

In the frog the alimentary canal, urinary ducts and genital ducts all open into a common chamber, the cloaca, which opens out through the cloacal aperture. The rabbit has separate anal and urogenital openings.

(a) Phytogeography

Phytogeography (plant geography) is the study of the distribution of plants over the earth's surface and the causes of that distribution.

(b) A collection of plants and animals

A community is an assemblage of populations of different plant and animal species living together in an area and interacting with one another.

(b) The ecological study of individual organisms

Autecology (species ecology) studies a single species or individual organism in relation to its environment. Synecology studies communities.

(a) Planktons

Plankton are microscopic organisms drifting in water. Phytoplankton are plants and zooplankton are animals.

(b) Ecological pyramid

An ecological pyramid is the graphic representation of the relationship between producers and the successive consumer levels, in terms of numbers, biomass or energy.

(a) Biosphere

The biosphere is the part of the earth, comprising the lithosphere, hydrosphere and atmosphere, where life exists. It includes all living organisms of the earth.

(c) Water

Water is a non-living (abiotic) component. Bacteria, Daphnia and Chlorella are living, so they are biotic.

(b) Consumer

Man cannot make his own food and depends on plants and animals, so he is a consumer, usually a primary consumer when eating plants and a secondary consumer when eating animals (omnivore).

(b) Asexual

Prokaryotes such as bacteria reproduce mainly by asexual methods, especially binary fission. Genetic exchange (conjugation, transformation, transduction) is not true sexual reproduction.

(b) Funaria

In the moss Funaria the sporogonium (sporophyte) contains chlorophyll and is partly photosynthetic when young. In Marchantia the sporophyte is not green and photosynthetic in the same way, and ferns have an independent sporophyte rather than a sporogonium.

(c) Thyroid

The thyroid gland selectively takes up iodide from the blood to make thyroxine (T4) and triiodothyronine (T3), which contain iodine.

(c) Autonomous nervous system

The sympathetic and parasympathetic divisions together form the autonomic (autonomous) nervous system, which controls involuntary functions of smooth muscle, cardiac muscle and glands.

(b) Goitre

Goitre is enlargement of the thyroid gland, usually caused by iodine deficiency or thyroid hormone imbalance, so it is an endocrine disorder. Pneumonia and typhoid are infections, and jaundice is a liver or blood disorder.

(c) Caecum

Rabbits are herbivores with a large caecum housing symbiotic bacteria that produce cellulase, which digests cellulose.

(d) Epiglottis

During swallowing, the epiglottis, a cartilaginous flap, closes the glottis (opening of the larynx) so food passes into the oesophagus rather than the respiratory tract.

(a) A, D, & E

The fat-soluble vitamins are A, D, E and K. Vitamins B-complex and C are water soluble.

(b) Deficiency disease

Rickets, a bone-softening disease of children, is caused by deficiency of vitamin D (and calcium/phosphorus).

(a) No enzymes

The liver secretes bile, which contains bile salts and pigments but no digestive enzymes. Bile salts emulsify fats and help lipase act.

(b) Fluorine

Fluorine converts hydroxyapatite in enamel into the harder fluorapatite, making teeth resistant to decay.

(d) Glucose

Glucose is the main fuel oxidised in cells (glycolysis and respiration) to produce ATP.

(b) 600ml

The human liver secretes about 600 ml of bile per day (roughly 500-1000 ml), and the gall bladder stores and concentrates it.

(d) D

Ultraviolet rays convert 7-dehydrocholesterol in the skin into cholecalciferol (vitamin D3).

(b) They respire during the day and night

Like animals, plants respire continuously, taking in oxygen and releasing carbon dioxide. During the day, respiration is masked by photosynthesis.

(b) Pancreas

The pancreas is exocrine because it secretes pancreatic juice through a duct. It is endocrine because its islets of Langerhans secrete insulin and glucagon into the blood.

(d) Water

Water makes up about 70-90% of protoplasm and is the medium for its chemical reactions.

(b) Iron

Haemoglobin contains iron (Fe²⁺) in the haem group, which binds oxygen.

(b) CO

Carbon monoxide binds haemoglobin about 200-250 times more strongly than oxygen, forming stable carboxyhaemoglobin.

(a) Plasma

Urea, a soluble nitrogenous waste made in the liver, is carried dissolved in blood plasma to the kidneys for excretion.

(c) Kidney

The kidneys reabsorb most of the filtered water, about 99% of the glomerular filtrate, mainly in the proximal convoluted tubule and also in the loop of Henle and collecting duct.

(d) Spleen

The spleen filters blood and destroys old red cells; it is not an excretory organ. The kidney, liver (bile pigments) and lung (CO2) excrete wastes.