Biology Grade 9 Ethiopia Flashcards

These vocabulary flashcards cover key terms from Units 1 through 6 of the Grade 9 Biology Student Textbook for Ethiopia, including concepts in cell biology, taxonomy, reproduction, human health, and ecology.

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 used by biologists to study living things, involving asking questions, suggesting possible answers (hypotheses), and testing for validity through experimentation.

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.

Autoclave

Laboratory equipment used to sterilize biological samples and contaminated materials by exposing them to high temperatures and highly pressurized steam.

Petri dishes

Flat dishes used with gelling culturing media, such as agar, for growing microorganisms.

Taxonomy

The science of naming, identifying, and classifying organisms based on their similarities and differences.

Taxonomic hierarchy

The process of arranging organisms into successive levels of biological classification, including kingdom, phylum, class, order, family, genus, and species.

Binomial nomenclature

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

Autotrophs

Organisms that use energy from sunlight to make their own food through photosynthesis; also known as producers.

Heterotrophs

Organisms that cannot make their own food and must consume others; also known as consumers.

Unicellular

Organisms made up of a single cell, such as bacteria.

Multicellular

Organisms composed of many cells of specialized types, such as plants and animals.

Prokaryotic cells

Unicellular organisms that lack a nucleus and membrane-bound organelles, typically between $1$ and 10\text{ }\text{\mu m} in size.

Eukaryotic cells

Relatively large and complex cells that contain a nucleus and other membrane-bound organelles, typically between $10$ and 100\text{ }\text{\mu m} wide.

Cell

The smallest and basic unit of living things that serves as the fundamental building block of all organisms.

Nucleus

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

Ribosomes

Small cellular structures found in large numbers that are responsible for synthesizing proteins.

Mitochondria

The 'powerhouse' of the cell, which features a double membrane and serves as the site for respiration and energy synthesis.

Chloroplasts

Double membrane-bounded organelles in green plants that contain chlorophyll to trap sunlight energy 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 higher water concentration to a region of lower water concentration through a semi-permeable membrane.

Active transport

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

Turgor pressure

The pressure exerted by the fluid in a cell's vacuole against the cell wall, helping plants retain an upright posture.

Plasmolysis

The process where a plant cell loses water in a hypertonic solution, causing the plasma membrane to shrink and pull away from the cell wall.

Asexual reproduction

The production of genetically identical offspring from a single parent without the involvement of gametes or fertilization.

Binary fission

A form of asexual reproduction common in bacteria where the unicellular parent divides into two approximately equal parts.

Parthenogenesis

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

Sexual reproduction

A process involving the fusion of the nuclei of two gametes (egg and sperm) to form a zygote.

Puberty

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

Nutrition

The process of taking in food and converting it into energy and other 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 the necessary nutrients in the correct amount and proportion to meet energy and growth requirements.

Deficiency disease

A health problem that occurs when a person does not have enough of a particular nutrient, such as scurvy or rickets.

Kwashiorkor

A deficiency disease caused by inadequate protein intake in the body, primarily affecting children.

Marasmus

A deficiency disease caused by inadequate carbohydrate and energy intake, resulting in extreme weight loss and muscle wastage.

Body mass index (BMI)

A guide to healthy body mass calculated using the formula: $\text{body mass (kg)} / \text{height}^2 \text{ (m}^2\text{)}$.

Drug

Any substance taken into the body that modifies or affects chemical reactions in the body.

Infectious diseases

Diseases caused by pathogens (such as bacteria, viruses, or protozoa) that can be transmitted from person to person.

Ecology

The branch of biology that deals with the study of the interactions among organisms and with their environment.

Ecosystem

A self-supporting unit consisting of a biological community and the non-living (abiotic) parts of the environment.

Abiotic factors

Non-living components of an ecosystem that influence the distribution of organisms, such as light, temperature, and water.

Biotic factors

Living components of an ecosystem that influence distributions, including predators, herbivores, parasites, and decomposers.

Biome

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

Ecological succession

The orderly, natural changes that take place in the communities of an ecosystem over time.