Biology, Human Body and Health for CUET General Aptitude

AnswerB · Mitochondrion

1. Mitochondria carry out aerobic respiration, breaking down glucose to release energy stored as ATP.

AnswerD · cell

1. Every living thing is made of one or more cells, and every life process happens in cells.

2. Cells group into tissues, tissues into organs and organs into systems.

AnswerA · Chloroplast

1. Chloroplasts contain the green pigment chlorophyll, which captures light energy to make food.

AnswerC · Cell wall

1. Plant cells have a rigid cell wall made of cellulose outside the cell membrane.

2. Animal cells have a cell membrane, nucleus and mitochondria too, but no cell wall.

AnswerB · Nucleus

1. The nucleus holds the DNA, arranged in chromosomes, which carries the instructions for the cell.

2. It directs growth, division and the making of proteins.

AnswerC · ribosomes

1. Ribosomes join amino acids together, following the instructions copied from DNA, to build proteins.

AnswerA · contain digestive enzymes that can break down the cell itself

1. Lysosomes hold powerful digestive enzymes that break down worn-out parts and germs.

2. If the cell is badly damaged, they burst and digest the cell itself, hence the name.

AnswerD · Robert Hooke

1. Robert Hooke saw tiny box-like compartments in cork and called them cells.

2. Robert Brown later discovered the nucleus, in 1831.

AnswerC · tendon

1. Tendons are strong, inelastic connective tissue that pull on bones when muscles contract.

2. Ligaments join bone to bone at joints.

AnswerA · Connective tissue

1. Connective tissues have cells spread in a matrix. Blood's matrix is the liquid plasma.

2. Blood connects and carries materials between all parts of the body, so it is a fluid connective tissue.

AnswerB · A nucleus enclosed in a membrane

1. Prokaryotic cells have DNA, ribosomes and a cell membrane, but the DNA lies free in the cytoplasm.

2. They have no membrane-bound nucleus (and no membrane-bound organelles such as mitochondria).

AnswerD · Nerve cell (neuron)

1. A neuron's long fibre, the axon, carries messages over long distances.

2. Some neurons run from the base of the spine to the toes, about a metre long.

AnswerA · More room for haemoglobin, so each cell carries more oxygen

1. Losing the nucleus leaves more space inside for haemoglobin, the oxygen-carrying protein, and gives the cell its flexible biconcave shape.

2. Without a nucleus they cannot divide and live only about 120 days.

AnswerD · Skin

1. The skin covers the whole body and is its largest organ by area and weight.

2. The liver is the largest internal organ and the largest gland.

AnswerC · 4

1. Two upper chambers (atria) receive blood and two lower chambers (ventricles) pump it out.

AnswerB · alveoli

1. The alveoli are millions of thin-walled sacs wrapped in blood capillaries.

2. Oxygen diffuses into the blood there and carbon dioxide diffuses out.

AnswerA · arteries

1. Arteries carry blood away from the heart under high pressure, so they have thick, elastic walls.

2. Veins bring blood back to the heart, and capillaries link the two.

AnswerC · Liver

1. The liver weighs about 1.5 kg in an adult and is the largest gland.

2. It makes bile, stores glycogen and removes toxins from the blood.

AnswerC · liver

1. The liver makes bile continuously; the gall bladder stores and concentrates it.

2. Bile breaks fat into small droplets (emulsification) so that enzymes can act on it.

AnswerB · nephrons

1. Each kidney has about a million nephrons.

2. Each nephron filters blood, takes back useful substances, and passes the waste (mainly urea) out as urine.

AnswerD · 120/80 mm Hg

1. Blood pressure is written as systolic over diastolic pressure.

2. About 120 mm Hg when the heart contracts and 80 mm Hg when it relaxes is taken as normal.

AnswerD · pancreas

1. Groups of cells in the pancreas, the islets of Langerhans, release insulin.

2. Too little insulin causes diabetes, in which blood sugar stays high.

AnswerA · Femur (thigh bone)

1. The femur, in the thigh, is the longest and strongest bone.

2. The stapes, in the middle ear, is the smallest. An adult has 206 bones.

AnswerB · Pituitary gland

1. The pituitary, at the base of the brain, releases hormones that control the thyroid, adrenal glands and sex organs.

2. It also makes growth hormone.

AnswerC · The pulmonary vein, carrying oxygen-rich blood from the lungs to the heart

1. Veins are defined by direction: they carry blood towards the heart.

2. The pulmonary vein brings freshly oxygenated blood from the lungs to the heart, so it is a vein carrying oxygen-rich blood.

AnswerB · Small intestine

1. Digestion is completed in the small intestine, which is about 6–7 m long.

2. Its inner wall has millions of villi that give a huge surface for absorbing digested food into the blood.

AnswerA · vitamin C

1. Vitamin C is needed to make collagen, which holds gums, skin and blood vessels together.

2. Citrus fruits, amla and guava are rich sources.

AnswerD · vitamin D

1. Vitamin D helps the body absorb calcium and phosphorus for bones.

2. The skin makes vitamin D in sunlight; milk, eggs and fish also supply it.

AnswerC · Iodine

1. The thyroid gland needs iodine to make the hormone thyroxine.

2. Without enough iodine the gland enlarges. Iodised salt prevents this.

AnswerD · iron

1. Iron is part of haemoglobin, which carries oxygen in red blood cells.

2. Too little iron means too little haemoglobin, so less oxygen reaches the tissues.

AnswerB · vitamin A

1. Vitamin A is needed to make the light-sensitive pigment in the rods of the retina.

2. Carrots, papaya, mango, green vegetables and milk are good sources.

AnswerC · helping food move through the gut and preventing constipation

1. Fibre is not digested, but it adds bulk and holds water.

2. This helps the intestines push food along and helps prevent constipation.

AnswerC · Vitamin K

1. Vitamin K helps the liver make the proteins that form a blood clot.

2. Green leafy vegetables are a rich source, and bacteria in the gut also make some.

AnswerA · vitamin B1 (thiamine)

1. Thiamine (vitamin B1) helps cells release energy from carbohydrates.

2. Beri-beri was common where people ate mostly polished white rice, which loses its thiamine-rich outer layer.

AnswerB · both proteins and calories (energy)

1. Marasmus is severe undernutrition: the diet lacks both energy and protein over months.

2. The body uses up its own fat and muscle, leaving the child thin and weak.

AnswerB · starch

1. Iodine turns blue-black in the presence of starch; this is the standard test for starch.

AnswerD · kwashiorkor

1. Kwashiorkor is caused mainly by a lack of protein even when calories are enough.

2. Fluid collects in the tissues, causing the swollen belly and puffy feet.

AnswerA · Fats

1. Fats give about 9 kcal per gram; carbohydrates and proteins about 4 kcal per gram each.

2. Vitamins give no energy; they help the body use the energy-giving nutrients.

AnswerC · Vitamins B and C

1. Vitamins A, D, E and K are fat-soluble and can be stored in the body's fat and liver.

2. The B group and vitamin C are water-soluble; they are not stored for long, so a regular supply is needed.

AnswerA · female Anopheles mosquito

1. Malaria is caused by a protozoan, Plasmodium.

2. Only the female Anopheles mosquito bites for blood and carries it between people.

AnswerD · Aedes

1. The Aedes mosquito, with black-and-white striped legs, breeds in clean stagnant water in coolers, pots and tyres.

2. It spreads dengue, chikungunya and Zika.

AnswerC · bacterium

1. TB is caused by the bacterium Mycobacterium tuberculosis and spreads through the air by coughing.

2. It is treated with a long course of antibiotics; the BCG vaccine protects young children.

AnswerB · contaminated water and food

1. Both are bacterial diseases carried in water or food contaminated with sewage.

2. Safe drinking water, handwashing and proper sanitation prevent them.

AnswerA · a virus

1. Antibiotics act on bacteria by attacking structures such as the cell wall.

2. Viruses lack these structures and multiply inside our own cells, so antibiotics do not affect them.

AnswerB · It trains the immune system with a harmless form of the germ, so the body can fight the real germ quickly

1. A vaccine contains a dead or weakened germ, or a part of it, that cannot cause the disease.

2. The body makes antibodies and memory cells against it, so a later infection is beaten before it causes illness.

AnswerD · Alexander Fleming

1. Fleming noticed that a Penicillium mould had killed the bacteria growing around it on a culture plate.

AnswerA · Polio

1. Under the Pulse Polio campaign, children under five were given oral polio vaccine drops.

2. India's last wild polio case was in January 2011, and the WHO certified the South-East Asia region, including India, polio-free in March 2014.

AnswerD · certain white blood cells of the immune system

1. HIV infects and kills helper T cells, a type of white blood cell that coordinates the immune response.

2. As they fall, the body cannot fight ordinary infections, which become dangerous.

AnswerC · Diabetes

1. Diabetes arises from a problem with insulin, linked to genes, diet and lifestyle, not from a germ.

2. TB is bacterial, and measles and chickenpox are viral; all three are infectious.

AnswerB · replace the water and salts lost in diarrhoea

1. Diarrhoea drains water and salts quickly, and dehydration is what makes it dangerous, especially for young children.

2. ORS replaces them; the sugar helps the gut absorb the salt and water.

AnswerA · the bite of an infected animal, most often a dog

1. Rabies is caused by a virus present in the saliva of infected animals.

2. It enters through a bite or scratch. Once symptoms appear it is almost always fatal, so the vaccine must be taken promptly after a bite.

AnswerC · AB

1. A person's plasma has antibodies against the A or B markers that their own cells lack.

2. Group AB has both markers, so its plasma has neither antibody and does not attack any donor's cells. AB is the universal recipient.

AnswerD · smallpox

1. Jenner noticed that milkmaids who caught mild cowpox did not get smallpox.

2. His cowpox vaccine protected against smallpox. The word vaccine comes from vacca, Latin for cow. Smallpox was declared eradicated worldwide in 1980.

AnswerD · Oxygen

1. Carbon dioxide + water → glucose + oxygen, in the presence of sunlight and chlorophyll.

2. The oxygen comes from splitting water, and it is released into the air.

AnswerA · chlorophyll

1. Chlorophyll, in the chloroplasts, absorbs mainly red and blue light and reflects green, which is why leaves look green.

AnswerC · xylem

1. Xylem vessels form continuous tubes from root to leaf and carry water and dissolved minerals upwards.

AnswerA · stomata

1. Stomata let carbon dioxide in for photosynthesis and let oxygen and water vapour out.

2. The guard cells open and close them.

AnswerB · phototropism

1. A tropism is growth in response to a direction-giving stimulus.

2. Growth towards light is phototropism; shoots show it and roots grow away from light.

AnswerB · phloem

1. Phloem carries dissolved food (mainly sucrose) from where it is made to where it is used or stored. This is called translocation.

2. Unlike xylem, phloem can carry material both up and down.

AnswerB · transpiration

1. Water evaporates from leaf cells and escapes through the stomata.

2. This transpiration pull helps draw water up the xylem from the roots and cools the plant.

AnswerD · pollination

1. Pollen is carried by insects, birds, wind or water from the anther (male part) to the stigma (female part).

2. Fertilisation comes later, when the male cell joins the egg inside the ovule.

AnswerC · nitrogen, which is scarce in the soil where it grows

1. Insectivorous plants grow in marshy, nitrogen-poor soils.

2. Digesting insects gives them the nitrogen they need to make proteins; they still make sugar by photosynthesis.

AnswerD · parasite

1. Cuscuta has no chlorophyll, so it cannot make its own food.

2. It pushes special roots into its host and takes food from it, harming the host: that is parasitism.

AnswerC · Ethylene

1. Ripe fruit gives off ethylene gas, which speeds up ripening in nearby fruit.

2. Auxin controls growth towards light, gibberellin makes stems lengthen, and cytokinin promotes cell division.

AnswerA · Light

1. Water softens the seed coat and activates enzymes; oxygen is needed for respiration; warmth lets enzymes work.

2. The seed lives on its stored food at first, so most seeds germinate even in the dark. Light becomes necessary once the seedling starts photosynthesis.

AnswerB · All the time, both day and night

1. Every living cell needs energy all the time, so respiration never stops.

2. Photosynthesis happens only in light. In the day it is faster than respiration, so plants give out oxygen overall; at night only respiration goes on.