Grade 9 Biology - Units B1-B4

Vocabulary flashcards covering the human circulatory system, reproduction, biodiversity, and plant nutrition from the Grade 9 Biology textbook.

Blood Circulatory System

The main transport system in the human body consisting of the blood, the heart, and the blood vessels.

Heart

A muscular organ, approximately the size of a clenched fist, that pumps blood into blood vessels to all parts of the body.

Blood Plasma

A pale yellowish liquid, making up approximately $55\%$ of blood, consisting mainly of water and dissolved substances such as glucose, salts, and gases.

Red Blood Cells (RBCs)

The most abundant blood cells ($41\%$) which contain the red pigment haemoglobin and carry oxygen throughout the body.

White Blood Cells (WBCs)

Large blood cells with a nucleus that protect the body against diseases by engulfing germs or producing antibodies.

Platelets

Small cell fragments found in blood that help in blood clotting to stop bleeding and prevent the entry of germs.

Haemoglobin

A red pigment found in RBCs that binds and carries oxygen throughout the body as oxy-haemoglobin.

Arteries

Blood vessels with thick walls and small lumens that carry oxygenated blood away from the heart under high pressure.

Veins

Blood vessels with thin walls, large lumens, and valves that carry deoxygenated blood towards the heart under low pressure.

Capillaries

Tiny, one-cell thick blood vessels that allow the exchange of substances, such as nutrients and $CO_2$, between blood and adjacent tissues.

Pulse

The result of stretching and recoiling of the artery walls every time the heart pumps blood.

Cardiovascular Diseases

Non-communicable diseases affecting the heart and blood vessels, such as heart attack and stroke.

Reproduction

The process of producing new individuals of the same kind or species to ensure the continuity of organisms on earth.

Species

A group of living organisms which can reproduce among themselves to produce fertile offspring.

Asexual Reproduction

A mode of reproduction involving a single parent that produces genetically identical offspring without the fusion of gametes.

Sexual Reproduction

A mode of reproduction involving two parents of different sexes and the fusion of male and female gametes.

Gametes

Specialised sex cells, namely sperms (male) and eggs or ova (female), produced by the reproductive systems.

Fertilisation

The process where a sperm cell fuses with an egg/ovum to produce a fertilised egg called a zygote.

Uterus

The organ in the female reproductive system where the foetus grows and develops.

Sexually Transmitted Diseases (STDs)

Infectious diseases that are transmitted through sexual contact, such as HIV/AIDS, syphilis, and gonorrhea.

HIV/AIDS

Acquired Immune Deficiency Syndrome caused by the Human Immunodeficiency Virus, which attacks white blood cells and weakens the immune system.

Biodiversity

The variety of species and their respective numbers found in a defined area.

Quadrat

A square frame made of wire, wood, or plastic used to estimate the number of plants or slow-moving animals in a habitat.

Invasive Alien Species

Non-native species that are introduced to an area and negatively affect the natural biodiversity.

Photosynthesis

The process through which green plants make food using $CO_2$ and water in the presence of sunlight and chlorophyll.

Chlorophyll

A green pigment found in chloroplasts that absorbs light energy necessary for photosynthesis.

Stomata

Small pores on the leaf surface that open to allow gas exchange and close to regulate water vapour loss.

Xylem

Vessels in the network of veins that carry water and minerals from the roots to the leaves.

Phloem

Vessels in the leaf veins that carry food, in the form of sugar (sucrose), from the leaves to all other parts of the plant.

Variegated Leaf

A leaf that has patches of green (where chlorophyll is present) and white or yellow parts (where chlorophyll is absent).