CIE iGCSE Biology - 1.1 Characteristics of Living Organisms Vocabulary

Vocabulary practice flashcards covering the key concepts and terms for CIE iGCSE Biology - 1.1 Characteristics of Living Organisms.

Movement

An action by an organism or part of an organism that results in a change of position or place.

Locomotion

Whole-body movement of an animal from one place to another, mainly to find food, escape predators, or reproduce.

Phototropism

A plant growth movement response in which shoots grow toward light.

Geotropism

A plant growth movement response in which roots grow downward into the soil in response to gravity.

Nastic movements

Non-directional plant movements triggered by touch or temperature, such as leaves folding in Mimosa.

Respiration

The chemical reaction in cells that breaks down nutrient molecules to release energy for metabolism.

Aerobic Respiration

A cellular reaction common in most organisms that breaks down glucose using oxygen: $\text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon dioxide} + \text{Water} + \text{Energy (ATP)}$ ($\text{C}_6\text{H}_{12}\text{O}_6 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{Energy}$).

Mitochondria

Tiny organelles inside living cells, known as the powerhouses of the cell, where respiration occurs to produce energy.

Metabolism

The total of all chemical reactions occurring within the body.

Breathing

The physical mechanism of taking in oxygen and releasing carbon dioxide, which supplies oxygen for cellular respiration.

Sensitivity

The ability of an organism to detect and respond to changes in the internal or external environment (also called responsiveness).

Stimulus

Any change in the internal or external environment that causes a response in an organism.

Photoreceptors

Receptors located in the eyes that detect light stimuli.

Mechanoreceptors

Receptors located in the ears that detect sound stimuli and maintain balance.

Chemoreceptors

Receptors located in the nose and tongue that detect chemical stimuli responsible for smell and taste.

Signal Transduction Pathway

The cellular response sequence involving (1) Reception of a stimulus by a receptor, (2) Transduction via relay proteins and second messengers, and (3) Response through activation of cellular responses.

Growth

A permanent increase in size and dry mass of an organism, caused by cell division and enlargement.

Mitosis

The process of cell division that produces new cells for growth and tissue repair.

Meristems

Special regions at the tips of roots and shoots in plants where active cell division and growth occur throughout life.

Dry mass

The total mass of an organism after all water weight has been removed, providing an accurate measurement of real growth.

Reproduction

The process that makes more organisms of the same kind, essential for the survival of a species.

Asexual reproduction

A method of reproduction involving just one parent that produces genetically identical offspring (clones) without gametes.

Sexual reproduction

A method of reproduction involving two parents and gametes, resulting in genetic variation among offspring.

Excretion

The removal from organisms of the waste products of metabolism and substances in excess of requirements.

Egestion

The removal of undigested food (such as feces) from the body, which is not metabolic waste.

Urea

A metabolic waste product formed in the liver from the breakdown of excess proteins/amino acids and excreted by the kidneys in urine.

Nitrogenous Waste Types

Products formed from the breakdown of nitrogen-containing amino groups ($-\text{NH}_2$), which include Ammonia ($\text{NH}_3$) in aquatic animals, Urea in mammals, and Uric acid in birds and reptiles.

Nutrition

The taking in of materials for energy, growth, and development.

Autotrophic nutrition

A mode of nutrition where an organism makes its own food using light energy via photosynthesis, such as green plants and algae.

Heterotrophic nutrition

A mode of nutrition where an organism obtains food by consuming other organisms, such as humans, animals, and fungi.