Biology Grade 9 Practice Flashcards

General Biology vocabulary flashcards covering introduction to biology, cell biology, human reproduction, nutrition, and ecology as per the Grade 9 curriculum.

Biology

The scientific study of life or living things, derived from the Greek words bios (life) and logos (study).

Scientific Method

A series of steps that involve asking questions, suggesting possible answers, and testing for the validity of the answers through experimentation.

Hypothesis

A proposed scientific explanation (possible answer) for a set of questions that must be testable.

Magnification

The number of times larger an image is than the real size of the object.

Resolution

The ability to distinguish between two separate points.

Microscope

An instrument used to observe and study objects that are too small to be seen by the naked eye.

Autoclave

Equipment used to sterilize biological samples and kill micro-organisms by exposing them to high temperatures and pressurized steam.

Taxonomy

The science of naming, identifying, and classifying organisms based on similarities and evolutionary relationships.

Taxonomic Hierarchy

The process of arranging organisms into successive levels: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Species

A group of organisms that can reproduce to produce fertile offspring.

Binomial Nomenclature

An internationally agreed system where the scientific name of an organism is made up of the genus and the specific epithet.

Cell

The smallest and most basic unit of living things.

Cell Theory

The principle stating that living organisms are composed of cells, cells are the smallest unit of life, and cells arise only from pre-existing cells.

Prokaryotic Cells

Unicellular organisms, usually between $1$ and $10$ micrometers, that lack a nucleus and membrane-bound organelles.

Eukaryotic Cells

Cells that contain a nucleus and other membrane-enclosed compartments, typically between $10$ and $100$ micrometers.

Nucleus

The largest organelle, surrounded by a double-membrane, that contains DNA and controls all cell activities.

Mitochondria

Often called the 'powerhouse' of the cell, these are the sites of respiration which produce energy.

Chloroplasts

Double membrane-bounded organelles in green plants that contain chlorophyll and serve as the site for photosynthesis.

Diffusion

The net movement of molecules or ions from a region of high concentration to a region of low concentration down a concentration gradient.

Osmosis

The diffusion of water molecules from a region of their higher concentration to a region of their lower concentration through a partially permeable membrane.

Active Transport

The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy.

Asexual Reproduction

The production of individuals from a single parent without the use of gametes (eggs or sperm).

Parthenogenesis

A form of asexual reproduction in which an unfertilized egg develops into an adult organism.

Puberty

The time or stage when secondary sex characteristics begin to develop and sexual maturity is reached.

Menstrual Cycle

The approximately monthly changes in the uterus including the flow of bits of uterine lining (menstruation).

Nutrition

The process of taking in food and converting it into energy and vital nutrients required for life.

Macronutrients

Nutrients required by the human body in large quantities, specifically carbohydrates, proteins, and fats.

Balanced Diet

A diet that contains all essential nutrients (carbohydrates, fats, proteins, vitamins, minerals, fiber, and water) in the correct amount and proportion.

Marasmus

A deficiency disease caused by inadequate carbohydrate content, resulting in children being extremely thin with an 'old-looking' face.

Kwashiorkor

A deficiency disease caused by inadequate protein content, often resulting in swelling of the abdomen and changes in hair color.

Body Mass Index (BMI)

A guide to healthy body mass calculated as $\text{BMI} = \frac{\text{body mass (kg)}}{\text{height}^2 (\text{m}^2)}$.

Chronic Bronchitis

An obstruction of the airways caused when tar from cigarette smoke irritates the lungs and stimulates excess mucus production.

Emphysema

A condition where the alveoli walls burst due to coughing, massively reducing the surface area for oxygen absorption.

Khat ($Catha edulis$)

A bushy plant whose leaves are chewed for a stimulant effect caused by the chemical compound cathinone.

Doping

The use of prohibited medications, drugs, or treatments in competitive sports to improve athletic performance.

Infectious Diseases

Diseases caused by organisms like bacteria, viruses, or protozoa that can be transmitted from person to person.

Pathogen

A disease-causing organism.

Vector

An organism, such as the Anopheles mosquito, that carries a disease-causing organism and transmits it to humans.

Ecology

The branch of biology dealing with interactions among organisms and with their environment.

Ecosystem

A self-supporting unit consisting of the physical environment (abiotic factors) and all living things (biotic factors) within it.

Habitat

The specific place in which a living thing lives within an ecosystem.

Niche

The combination of the job an organism does and the place in which it lives.

Biome

A major terrestrial or aquatic life zone characterized by vegetation type or the physical environment.

Ecological Succession

The process where a disturbed area is colonized by a variety of species that are gradually replaced by others until a climax community is formed.

Mutualism

An ecological interaction that benefits individuals of both interacting species ($+/+$).

Commensalism

An interaction that benefits one species while the other is neither helped nor harmed ($+/0$).

Parasitism

An interaction where one organism (the parasite) derives nourishment from another (the host) which is harmed ($+/-$).