Living Things and Air Practice Flashcards

Vocabulary flashcards covering key terms, definitions, gas tests, and ecological concepts from the Unit 7 Living Things and Air transcript.

Atmosphere

The essential layer of air surrounding the Earth that enables living things to survive.

Air

A mixture of gases composed of $78\%$ nitrogen, $21\%$ oxygen, $0.9\%$ noble gases (mainly argon), $0.03\%$ carbon dioxide, and $0.07\%$ water vapour and other gases.

Noble gases

A group of very unreactive gases in air—also called inert gases—which includes helium, neon, argon, krypton, xenon, and radon.

Test for oxygen

A diagnostic chemical test in which a gas relights a glowing splint or causes a burning splint to burn more brightly.

Test for carbon dioxide

A diagnostic chemical test in which a gas turns hydrogencarbonate indicator from red to yellow and turns limewater from colourless to milky.

Test for water and water vapour

A test in which water or water vapour turns dry cobalt chloride paper from blue to pink.

Photosynthesis

The process by which green plants make food (glucose) and oxygen from carbon dioxide and water using light energy absorbed by chlorophyll.

Chlorophyll

A green pigment present in chloroplasts that absorbs light energy required for photosynthesis.

Starch

A carbohydrate formed from excess glucose for temporary storage in plants, which turns iodine solution from brown to blue-black.

Destarching

The procedure of keeping a plant in the dark for at least $48\,\text{hours}$ so that stored starch in leaves is fully converted into glucose before an experiment.

Soda lime

A corrosive chemical substance mainly composed of calcium hydroxide used to absorb carbon dioxide from the air.

Producer

An organism, such as a green plant, that can manufacture its own food through photosynthesis.

Consumer

An organism, such as an animal, that cannot manufacture its own food and obtains energy by feeding on plants or other animals.

Food chain

A diagram representing the feeding relationships and the flow of energy among living organisms starting from the Sun.

Respiration

A chemical process taking place in body cells where glucose and oxygen react to release energy, producing carbon dioxide and water.

Stomata

Tiny pores on the leaf epidermis through which gas exchange occurs in plants.

Guard cells

Pairs of specialized cells surrounding each stoma that control its opening and closing by changing water content.

Inhaled air

Air drawn into the lungs containing $21\%$ oxygen, $0.03\%$ carbon dioxide, variable water vapour, and a lower temperature relative to exhaled air.

Exhaled air

Air expelled from the lungs containing $16\%$ oxygen, $4\%$ carbon dioxide, saturated water vapour, and a higher temperature relative to inhaled air.

Air sacs

Microscopic structures surrounded by blood capillaries at the ends of bronchioles in the lungs where human gas exchange takes place.

Tar

A brown sticky substance in cigarette smoke that deposits in the breathing system, causes cilia to stick together, stimulates excess mucus production, and causes lung cancer.

Nicotine

An oily liquid in cigarette smoke that causes addiction and increases heart rate and blood pressure, leading long-term to heart diseases.

Carbon monoxide

A colourless, odourless, and toxic gas found in cigarette smoke and air pollution that reduces the oxygen content in blood.

Greenhouse effect

The natural process where atmospheric greenhouse gases trap heat radiated from the Earth's surface to maintain a warm climate.

Global warming

The overall increase in the average temperature of the Earth caused by an enhanced greenhouse effect due to elevated atmospheric carbon dioxide.

Air Quality Health Index (AQHI)

A scale from $1$ to $10$ and $10+$ reported by the EPD in Hong Kong to inform the public of short-term health risks from air pollution.

Vertical farming

A high-density farming method where crops are grown on stacked racks inside buildings using controlled LED lighting, hydroponics, and drip irrigation.