Life Processes: 36 MCQs with answers

C · Digestion

Digestion is defined as the process of breaking complex food components into simpler forms in the body.

C · Small intestine

The small intestine is about 6 metres long, making it the longest part of the alimentary canal.

C · Alveoli

Alveoli are small balloon-like sacs in the lungs where exchange of oxygen and carbon dioxide occurs.

D · Breathing

Breathing is the physical process of inhaling and exhaling air, while respiration is the chemical process of releasing energy.

D · Animals that chew cud

Ruminants, such as cows and buffaloes, partially chew grass, swallow it, and later bring it back to the mouth for thorough chewing.

B · Fish

Fish have specialised structures called gills for gas exchange in water.

B · Chewing of food by teeth

Mechanical digestion refers to the physical breakdown of food, such as chewing by teeth.

B · False

The small intestine is about 6 metres long, while the large intestine is about 1.5 metres long, so the small intestine is longer.

A · True

Earthworms use their moist skin for the exchange of oxygen and carbon dioxide.

B · To break down food

The primary function of the digestive system is to break down food into simpler forms that can be absorbed by the body.

B · Carbohydrates

Carbohydrates are primarily used for energy in animals, providing a quick source of fuel.

B · Lungs

The lungs are the main organs responsible for gas exchange in mammals, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled.

C · Ingestion

Ingestion is the process of taking food into the body, which is the first step in the digestive process.

B · Aerobic respiration

Aerobic respiration occurs when oxygen is used to break down food, producing energy.

B · To absorb nutrients

The small intestine's primary role is to absorb nutrients from digested food into the bloodstream.

A · Carbon dioxide

Carbon dioxide is a waste product of respiration, produced when food is broken down for energy.

A · To assist in breathing

The diaphragm assists in breathing by contracting and relaxing to change the volume of the thoracic cavity.

D · Digestion

Digestion is the process of breaking down food into smaller molecules that can be absorbed by the body.

C · Fish

Fish primarily use gills for respiration, allowing them to extract oxygen from water.

A · It neutralises acids and breaks down fats into tiny droplets.

Bile, secreted by the liver, is mildly basic and neutralises acids from the stomach; it also breaks down fats into tiny droplets to aid digestion.

D · It absorbs water and some salts from undigested food.

The large intestine absorbs water and some salts from undigested food, making the waste semi-solid (stool).

C · Breathing is a physical process, respiration is a chemical process.

Breathing involves physical movements of air, while respiration is a chemical process that releases energy from glucose.

D · The lungs

In the model, the balloons represent the lungs, and the rubber sheet represents the diaphragm.

D · It protects the stomach lining from acid.

Mucus protects the stomach lining from the acidic environment, preventing damage.

C · It grinds food, often with the help of grit.

The gizzard is a chamber where food is broken down by contraction and relaxation of its walls, often aided by small stones (grit).

D · Oxygen from alveoli passes into blood, and carbon dioxide from blood passes into alveoli.

In alveoli, oxygen from the air passes into the blood, while carbon dioxide from the blood is released into the alveoli to be exhaled.

A · Enzymes break down food into simpler molecules.

Enzymes are biological catalysts that speed up the breakdown of food into simpler molecules, facilitating digestion.

A · Alveoli are surrounded by capillaries, increasing surface area.

The alveoli are surrounded by capillaries, which increases the surface area for gas exchange, allowing for efficient oxygen and carbon dioxide transfer.

C · Aerobic respiration

Aerobic respiration occurs in the mitochondria, where glucose is broken down with oxygen to produce energy.

B · Mechanical digestion breaks food into smaller pieces without chemical change.

Mechanical digestion physically breaks food into smaller pieces without altering its chemical structure, while chemical digestion involves enzymatic breakdown.

B · Carbohydrates

The small intestine is primarily responsible for the absorption of carbohydrates, proteins, and fats, but it is especially efficient at absorbing simple sugars from carbohydrates.

C · To enhance the efficiency of gas exchange.

A high surface area in the respiratory system, particularly in the alveoli, enhances the efficiency of gas exchange by allowing more oxygen and carbon dioxide to be exchanged.

B · To break down carbohydrates.

Amylase is an enzyme that specifically breaks down carbohydrates into simpler sugars, aiding in the digestion process.

C · Cellular respiration converts glucose into energy in the form of ATP.

Cellular respiration converts glucose into energy (ATP) through various biochemical pathways, primarily in the mitochondria of cells.

B · Herbivores have specialized teeth for grinding plant material.

Herbivores have specialized teeth, such as molars, that are adapted for grinding plant material, which is necessary for breaking down tough fibers.

C · Reabsorption of water and formation of feces.

The large intestine primarily reabsorbs water and forms feces, playing a crucial role in maintaining fluid balance in the body.