SCIENCE G7_U7 & 8

Microorganism

A living organism so small that it can only be seen clearly using a microscope

Single-celled

Organisms made of only one cell

Viruses

Organisms even smaller than bacteria that are usually not classified as microorganisms because they do not fulfill all the criteria for living things

.Bacteria

Microorganisms that are found everywhere; each bacterium is a single cell much smaller than animal or plant cells. While most are harmless, some can cause illness

Fungi

Organisms that are not always microscopic; large versions include mushrooms and toadstools, which are made of a tangle of thin threads

DDT

A persistent chemical used to kill mosquitoes; it stays in the environment for a very long time and can harm other animals, such as birds of prey, by making their eggshells thin

Yeast

A microscopic fungus made of single cells rather than threads; it feeds on sugar, such as those found in grapes

Algae

A specific kind of microorganism

Protozoa

A specific kind of microorganism; for example, the organism that causes malaria is a microscopic protozoan

Colony

A visible collection of many cells formed when a single microorganism divides repeatedly

Agar jelly

A special kind of nutrient-rich jelly used in laboratories to grow microorganisms

Petri dish

A shallow dish used by scientists to hold agar jelly for growing microorganisms

Sterile

A state where all living organisms have been killed to prevent unwanted growth

Ecology

The study of organisms in their environment

Food chain

A diagram using arrows to show how energy is transferred from the Sun to a producer and then to consumers

Food web

A model showing how multiple food chains are connected by feeding relationships within the same place

Producer

The first organism in a food chain, usually a plant, which uses energy from the Sun to make its own food

Consumer

Animals that must eat ready-made food (plants or other animals) to obtain energy

Herbivore

A consumer that eats only plants

Carnivore

A consumer that eats other animals

Predator

An animal that catches, kills, and eats other animals

Prey

Animals that are eaten by predators

Decomposer

Organisms, including some bacteria and microscopic fungi, that break down organic matter for food

Decay / Rot

The process where decomposers break down substances, often making them brown and soft

Organic matter

Any substance that has been made by a living organism

Mould

A common name for microscopic fungi that grow on the surface of decaying matter, like bread or fruit

Nutrients

Substances used by living organisms for energy or growth; decomposers return these to the soil when they break down organic matter

Dung

Animal waste that serves as organic matter for decomposers to break down

Chemical reaction

A process where new substances are formed; atoms are combined and bonded in new ways

Reactants

The original substances that react together

Product

The new substance(s) made during the reaction

Neutralisation

A chemical change where an acid and an alkali react to cancel each other out, resulting in a neutral solution (pH 7)

Burette

A piece of laboratory equipment used to add liquid (like acid) very accurately, a few drops at a time

Indigestion

Discomfort caused by the stomach producing too much hydrochloric acid

Digest

The process of breaking down food, which requires specific acidic conditions in the stomach

Filtrate

The liquid that passes through filter paper during filtration

Remedy

A treatment for an illness, such as antacids used to neutralise excess stomach acid

Variable

Any factor that can change in an investigation; for a fair test, scientists change one, measure one, and keep the others the same

Cloudy

The appearance of limewater when it reacts with carbon dioxide to form a solid

Glowing (Splint)

A wooden stick that is no longer flaming but still hot; it will relight if placed in oxygen

Precipitate

A solid that forms when two solutions (liquids) are mixed together

Oxides

New substances (compounds) formed when an element, like carbon or magnesium, combines with oxygen during burning

Fair test

An investigation where scientists change only one variable, measure another, and keep all other variables the same to ensure the results are reliable

Limewater

A solution of calcium hydroxide used to test for carbon dioxide; it turns cloudy when the gas is present

How do you test for hydrogen gas?

You light a splint and place it in the mouth of the test tube; if hydrogen is present, it will burn with a squeaky pop

.How do you test for carbon dioxide gas?

You bubble the gas through limewater (calcium hydroxide solution); if carbon dioxide is present, the limewater will turn cloudy because a solid precipitate of calcium carbonate is formed

.How do you test for oxygen gas?

You place a glowing splint into the mouth of the test tube; if the gas is oxygen, the splint will relight.