Biology – Life Processes

Question–and–Answer flashcards covering definitions, processes, structures and functions related to nutrition, respiration, transportation and excretion in plants and animals.

What are life processes in living organisms?

Basic activities such as nutrition, respiration, transportation and excretion that are necessary to maintain life.

Which four basic life processes are essential for survival?

Nutrition, respiration, transportation and excretion.

Why is nutrition vital to all other life processes?

It supplies the energy required to carry out the other life processes.

Define nutrition.

The process of taking in food and utilizing it in the body for life processes.

What is autotrophic nutrition? Give an example.

Mode of nutrition where organisms make their own food; e.g., green plants.

What is heterotrophic nutrition? Give an example.

Mode in which organisms depend, directly or indirectly, on autotrophs for food; e.g., animals or fungi.

Name the three main types of heterotrophic nutrition.

Saprophytic, parasitic, and holozoic nutrition.

What happens in saprophytic nutrition?

Organisms secrete enzymes onto dead organic matter, digest it externally and absorb the nutrients; e.g., fungi, yeast, mushrooms.

Explain parasitic nutrition.

One organism (parasite) lives on or inside another organism and derives food without killing it; e.g., Cuscuta, lice, leeches.

Describe holozoic nutrition.

Organism ingests solid food, then digests, absorbs and egests it; e.g., Amoeba, humans.

List the sequential steps of holozoic nutrition.

Ingestion, digestion, absorption, assimilation and egestion.

Define photosynthesis.

Process by which green plants convert CO₂ and water into carbohydrates (starch) in the presence of sunlight and chlorophyll, releasing oxygen.

What are the main product and by-product of photosynthesis?

Product: carbohydrate (glucose/starch); by-product: oxygen gas.

State four raw materials or conditions necessary for photosynthesis.

Carbon dioxide, water, sunlight and chlorophyll (photosynthetic pigment).

Where in a plant cell does photosynthesis occur?

In the chloroplasts of green tissues (leaves and young stems).

List the three basic steps in the mechanism of photosynthesis.

1) Absorption of light energy by chlorophyll, 2) Conversion to chemical energy with splitting of water, 3) Reduction of CO₂ to form carbohydrates.

Give two major importances of photosynthesis.

Provides food for living organisms and purifies air by consuming CO₂ while releasing oxygen; also converts light energy to chemical energy.

How does Amoeba take in food?

By forming pseudopodia around food particles to create a food vacuole (phagocytosis).

What occurs inside the food vacuole of Amoeba?

Digestion and absorption of food; undigested residues are later expelled out of the cell.

Name the two main parts of the human digestive system.

The alimentary canal and associated digestive glands (liver, pancreas, etc.).

Where does digestion start in humans and which enzyme acts first?

In the mouth (buccal cavity) with the action of salivary amylase.

What type of movement pushes food from mouth to stomach?

Peristaltic movement through the oesophagus.

Which organs add digestive juices into the small intestine?

Liver (bile), gall bladder (stored bile) and pancreas (pancreatic juice).

Where are remaining nutrients and water absorbed in the digestive tract?

In the large intestine; wastes are then eliminated via rectum and anus.

Define respiration in biological terms.

Process of releasing energy by oxidation of food, typically using oxygen and releasing carbon dioxide.

Differentiate between gaseous exchange and cellular respiration.

Gaseous exchange (breathing) is physical intake of O₂ and release of CO₂; cellular respiration is biochemical breakdown of food to release energy inside cells.

Trace the pathway of air from nostrils to alveoli.

Nostrils → nasal passage → nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.

What is the primary function of alveoli?

They provide a large surface for exchange of oxygen and carbon dioxide between air and blood.

State three mechanical changes during inhalation.

Thoracic cavity expands; ribs move upward; diaphragm flattens—lung volume rises and air enters.

State three mechanical changes during exhalation.

Thoracic cavity contracts; ribs move downward; diaphragm becomes dome-shaped—lung volume decreases and air exits.

Through which three structures do plants exchange respiratory gases?

Stomata (leaves), lenticels (stem) and general surface of roots.

List the three main components of the human circulatory system.

Heart, blood vessels (arteries & veins) and blood (also lymph).

How many chambers does the human heart have and what are they called?

Four chambers: two atria (upper) and two ventricles (lower).

Why are ventricular walls thicker than atrial walls?

Because ventricles pump blood to lungs or the entire body, requiring greater force.

State two structural/functional features of arteries.

Thick-walled, carry oxygenated (pure) blood away from heart, and lack valves.

State two structural/functional features of veins.

Thin-walled, carry deoxygenated (impure) blood toward the heart, and possess valves to prevent backflow.

What key role do capillaries play?

They connect arteries and veins and facilitate exchange of nutrients, gases and wastes between blood and tissues.

Match each blood component with its main function: plasma, RBC, WBC, platelets.

Plasma: transports dissolved substances; RBC: carries oxygen; WBC: defends against microbes; Platelets: clotting of blood.

What is lymph and give two of its functions.

Yellowish fluid that escapes from capillaries; carries absorbed fats from intestine and returns excess interstitial fluid to the blood.

Define double circulation and name its two circuits.

Blood passes through the heart twice per body cycle; includes pulmonary (heart ↔ lungs) and systemic (heart ↔ body) circulation.

Name the two conducting tissues responsible for transport in plants.

Xylem and phloem.

What is transpiration and list two of its roles.

Loss of water vapour from plant surfaces; creates upward pull for water/minerals and helps regulate plant temperature.

What is translocation in plants?

Transport of food (sucrose, etc.) from leaves to other plant parts via phloem.

List the organs that form the human excretory system.

Two kidneys, two ureters, urinary bladder and urethra.

What is a nephron?

Functional and structural filtration unit of the kidney.

Name the three sequential steps in urine formation.

Glomerular filtration, tubular re-absorption and tubular secretion.

What is haemodialysis and who needs it?

Purification of blood through an artificial kidney; used for patients with kidney failure.

Give three ways plants excrete waste products.

Release O₂ during photosynthesis; lose H₂O by transpiration; store wastes in leaves/bark that later fall, or as gums/resins, or secrete them into surrounding soil.