Biology for CSEC Examinations - Section A & B Review

Vocabulary flashcards covering major biological concepts from Section A (Living Organisms in the Environment) and Section B (Life Processes and Disease) for CSEC Biology.

Irritability

The ability of living organisms to respond to changes in their internal environment and the world around them to increase chances of survival.

Prokaryotes

The most ancient group of organisms, commonly called bacteria, characterized by cells where chromosomes are not enclosed in a nucleus.

Saprotrophic Nutrition

A mode of feeding where organisms, like fungi and decomposers, obtain energy from dead organic material by digesting it outside the body using enzymes.

Xerophytes

Plants adapted to live in areas where water is in short supply, often featuring reduced leaves, sunken stomata, or thick waxy cuticles.

Ecosystem

A self-sustaining system of organisms interacting with each other and their physical environment.

Trophic Level

The position an organism occupies in a food chain (e.g., producer, primary consumer, secondary consumer).

Bioaccumulation

The process where toxic chemicals like pesticides accumulate in higher concentrations in the tissues of organisms at higher trophic levels.

Global Warming

The increase in Earth's temperature resulting from an enhanced greenhouse effect due to increased proportions of gases like $CO_2$ and methane.

Nitrogen Fixation

The process carried out by bacteria like Rhizobium and Azotobacter that converts nitrogen gas from the air into nitrates that plants can absorb.

Carrying Capacity

The maximum population size of a species that can be sustained over a period of time by a particular environment.

Biodegradable

Materials that can be broken down naturally into simpler, harmless forms by the action of microorganisms.

Eutrophication

The process where excess nutrients in water lead to rapid algal growth, oxygen depletion, and the death of aquatic organisms.

Organelle

Specialized structures found within a cell, such as mitochondria or chloroplasts, that perform specific functions to keep the cell alive.

Osmosis

The diffusion of water molecules across a selectively permeable membrane from a region of high water concentration to a region of lower water concentration.

Limiting Factor

An environmental factor (like light intensity or $CO_2$ concentration) that is in the shortest supply and restricts the rate of photosynthesis.

Balanced Diet

A diet containing the correct proportions of carbohydrates, proteins, lipids, vitamins, minerals, water, and fiber needed to maintain health.

Peristalsis

A wave of muscle contraction that moves food downward along the alimentary canal.

Villi

Finger-like projections on the wall of the ileum that increase surface area for the efficient absorption of nutrients into the blood.

Aerobic Respiration

The enzyme-catalyzed reaction in mitochondria that releases energy from glucose using oxygen, summarized as: $C_6H_{12}O_6 + 6O_2 <br /> ightarrow ext{energy} + 6H_2O + 6CO_2$.

Oxygen Debt

The amount of oxygen required after strenuous exercise to break down the lactic acid produced during anaerobic respiration in muscles.

Alveoli

Tiny air sacs in the lungs where gaseous exchange occurs between the air and the blood capillaries.

Homeostasis

The maintenance of a constant internal environment (e.g., temperature, blood glucose) despite changes in the external environment.

Nephron

The basic functional unit of the kidney responsible for pressure filtration and selective reabsorption to produce urine.

Antagonistic Muscles

Pairs of muscles, such as the biceps and triceps, that work together by one contracting while the other relaxes to move a bone.

Synapse

The small gap between the ends of two neurones where electrical impulses are converted into chemical signals to be transmitted.

Accommodation

The adjustment of the lens shape by the ciliary muscles to focus on objects at different distances.

Placenta

An organ that allows for the exchange of nutrients, oxygen, and waste products between the mother's blood and the fetus without them mixing.

Pollination

The transfer of pollen grains from an anther to a stigma of a flower of the same species.

Mitosis

Cell division resulting in two genetically identical diploid ($2n$) cells, used for growth, repair, and asexual reproduction.

Allele

One of the alternative forms of a gene that occupies a specific position on a chromosome.