B.3 - Gas Exchange and Transport

Definitions of key terms

Cellular Respiration

The process occurring in all living cells that releases energy in the form of ATP.

Aerobic Respiration

A type of cellular respiration that requires oxygen to occur and produces carbon dioxide as a waste product.

Gas Exchange

The process by which living organisms acquire oxygen from the environment and release carbon dioxide back into the surroundings.

Diffusion

The process by which gases are exchanged between living organisms and their environment, influenced by factors like surface area and concentration gradient.

Gas Exchange Surfaces

Surfaces in organisms that facilitate the exchange of oxygen and carbon dioxide, possessing properties like permeability and a large surface area.

Ventilation

The mechanism essential for the exchange of gases in the lungs, involving inspiration (breathing in) and expiration (breathing out).

Spirometer

An apparatus used to measure lung volumes and investigate the effect of exercise on ventilation.

Tidal Volume

The volume of air inhaled and exhaled during normal breathing, which can increase during exercise.

Vital Capacity

The total amount of air exhaled after taking a deep breath, calculated by adding tidal volume, inspiratory reserve volume, and expiratory reserve volume.

Leaf Adaptations for Gas Exchange

Adaptations in plant leaves like stomata, mesophyll tissue, and vascular tissue that facilitate gas exchange and photosynthesis.

Stomata

Pores in the leaf epidermis allowing gas exchange during photosynthesis

Transpiration

Loss of water vapor through stomata during gas exchange, aiding in cooling and mineral uptake

Guard cells

Cells that regulate stomatal opening and closing to balance gas exchange and water loss

Turgor pressure

Pressure in plant cells due to water uptake, supporting leaves and non-woody stems

Capillaries

Small blood vessels with a single endothelial cell layer for efficient exchange of substances

Arteries

Blood vessels carrying blood away from the heart with thick muscular walls and elastic tissue

Veins

Blood vessels carrying blood to the heart at low pressure, with valves to prevent backflow

Transpiration stream

Movement of water from xylem vessels to replace water lost during transpiration

Capillary Action

The movement of water in a narrow tube due to adhesion to the tube's walls.

Transpiration Pull

The pulling force created in xylem vessels by tension when water moves into leaves, allowing water to move against gravity.

Cohesion-Tension Theory

The theory explaining the movement of water in plants due to cohesion between water molecules and tension in xylem.

Transpiration Stream

The continuous upward flow of water in xylem vessels of plants.

Xylem Vessels

Vascular tissues responsible for transporting water and mineral ions from roots to leaves in plants.

Atherosclerosis

The process of arterial narrowing due to the build-up of fatty deposits, leading to reduced blood flow.

Coronary Heart Disease

A condition resulting from atherosclerosis, potentially causing heart attacks due to blocked arteries.

Epidemiological Studies

Research on human populations to evaluate the correlation between risk factors and coronary heart disease.

Controlled Experiment

A study design involving different groups to establish causal links between risk factors and diseases.

Validity of Results

Ensuring that research outcomes are accurate, unbiased, and measure what they intend to, considering various factors like sample size and study design.