Grade 9 Biology: Blood Circulation, Reproduction, Biodiversity & Plant Nutrition

Comprehensive vocabulary flashcards covering the human circulatory system, human reproduction, biodiversity, and plant nutrition (photosynthesis) based on the Grade 9 Biology lecture notes.

Blood Circulatory System Components

The three main components are blood, blood vessels, and the heart.

Plasma

A pale yellowish liquid consisting of water and dissolved substances like glucose, salts, gases, proteins, and waste, making up $55\%$ of blood volume.

Haemoglobin

The red pigment found in red blood cells that is responsible for carrying oxygen.

Red Blood Cell (RBC) Adaptations

They lack a nucleus to carry more haemoglobin and have a flattened, concave shape to provide a large surface area for rapid oxygen diffusion.

White Blood Cells (WBC)

Cells that protect the body against diseases by engulfing (digesting) germs or by making antibodies to destroy them.

Platelets

Small cell fragments in the blood that aid in clotting to stop excessive blood loss and prevent germ entry.

Lumen

The central hole in a blood vessel through which blood flows.

Arteries

Thick-walled blood vessels with small lumens that carry oxygenated blood under high pressure away from the heart.

Veins

Thin-walled blood vessels with large lumens and valves that carry deoxygenated blood under low pressure towards the heart.

Capillaries

Blood vessels with walls only one cell thick that allow the exchange of food, oxygen, and waste products between blood and tissue cells.

Pulmonary Artery

The specific artery that carries deoxygenated blood from the heart to the lungs.

Pulmonary Vein

The specific vein that carries oxygenated blood from the lungs to the heart.

Heart Beat

An event that occurs every time the muscles of the heart contract.

Pulse

The stretching and relaxation of artery walls to maintain blood flow under high pressure; $1\text{ heart beat} = 1\text{ pulse}$.

Average Pulse Rate

Between $60-100$ times per minute for a child aged $12-16$ years.

Cardiovascular Diseases

Diseases of the heart and blood vessels, such as heart attack and stroke.

Reproduction

The process of producing new individuals of the same species to ensure survival, continuity, and prevent extinction.

Asexual Reproduction

Reproduction involving one parent and no fusion of gametes, resulting in identical offspring; examples include bacteria, fungi (Yeast), and amoeba.

Sexual Reproduction

Reproduction involving two parents and the fusion of gametes, resulting in non-identical offspring; occurring in most plants and animals.

Gametes

Specialized sex cells, known as sperm in males and eggs or ova in females.

Fertilisation

The process whereby male and female gametes fuse to form a zygote ($\text{Sperm} + \text{Egg} \rightarrow \text{Zygote}$).

Urethra

A tube in males that carries urine or semen containing sperms to the outside of the body.

Scrotum

A sac-like structure that holds the testes outside the male body.

Oviduct

The specific site in the female reproductive system where fertilisation occurs.

Uterus

The organ where the foetus grows and develops during pregnancy.

Vagina

The place where sperms are released during intercourse and also serves as the birth canal.

Communicable Diseases

Diseases caused by pathogens (germs) that spread from one person to another through direct or indirect contact.

Pathogens

Harmful microorganisms responsible for diseases, including bacteria, fungi, viruses, and protists.

HIV/AIDS

A sexually transmitted disease caused by the HIV virus, preventable by using condoms and avoiding multiple sex partners.

Ecosystem

The interaction of living things with each other and their non-living environment.

Biodiversity

The large variety of living organisms, including plants, animals, bacteria, protista, and fungi, in a defined area.

Quadrat

A tool used to count and estimate the number of plants, algae, and slow-moving animals in a habitat.

Species

A group of living organisms capable of reproducing among themselves.

Deforestation

The clearing of large areas of forests for timber, paper, agriculture, or urban development, leading to habitat loss and potential extinction.

Pollution

The release of harmful substances called pollutants (air, water, soil, noise, heat) into the environment.

Global Warming

An abnormal rise in the earth's temperature caused by gases such as $CO_2$ and methane.

Eutrophication

The excessive growth of algae in water bodies that results in a decrease of oxygen, often killing aquatic life.

Invasive Alien Species

Non-native organisms like rats, monkeys, or Chinese Guava introduced unnaturally to an ecosystem that compete with or prey on native species.

Conservation of Biodiversity

The protection and preservation of variety in an ecosystem via nature reserves, captive breeding, botanical gardens, and enforcing laws.

Photosynthesis

The process by which plants use $CO_2$ and water in the presence of sunlight and chlorophyll to produce food (glucose) and oxygen.

Xylem

Vascular tissue that carries water from the roots to the leaf cells.

Phloem

Vascular tissue that transports food (sucrose) throughout the plant.

Stomata

Pores in the leaf that allow for gas exchange (entry of $CO_2$ and exit of oxygen).

Diffusion

The movement of particles from a region of high concentration to a region of low concentration, such as $CO_2$ entering a leaf.

Starch Test

A procedure using iodine solution where a blue-black colour indicates that a leaf has carried out photosynthesis, while a brown/yellow colour shows the absence of starch.

Ethanol in Starch Testing

Used to remove chlorophyll from the leaf; it must be heated in a water bath because it is highly flammable.