Year 9 Science Revision Flashcards

Flashcards covering key concepts from Year 9 Science, including Kingdoms, Cells, Pathogens, Photosynthesis, Variation, Adaptation, Ecology, Forces, and Energy.

What cell parts are present in all five kingdoms (prokaryotes, protoctists, fungi, plants, and animals)?

Cytoplasm and cell membrane

Which kingdoms contain unicellular organisms?

Prokaryotes and protoctists

Why can't unicellular organisms grow too large?

Diffusion becomes too slow, and they can't get enough substances throughout the cell due to a large surface area: volume ratio.

How are bacterial pathogens treated?

With antibiotics

How do vaccines work?

They cause white blood cells to become able to destroy some bacteria or viruses, making us immune.

What is the basic structure of a virus?

A strand of genes inside a protein coat (and often a fat envelope).

How do microscopic fungi like yeast reproduce?

Asexually by budding

What are the products of anaerobic respiration (fermentation) in yeast?

Carbon dioxide and ethanol (alcohol)

What is produced when bacteria ferment milk?

Lactic acid

How do bacteria and fungi feed?

By releasing enzymes into their surroundings to digest large organic molecules, then absorbing the digested molecules.

What role do photosynthesizing protoctists play in a food chain?

They are in the producer trophic level.

Name three ways protoctists move.

Using pseudopods (e.g., Amoeba), cilia (e.g., Paramecium), or flagella (e.g., Euglena).

List three things microorganisms need to grow well.

Warmth, food, and moisture (some also need light or oxygen).

What is a limiting factor in population growth?

Something that stops a population from increasing further.

What role do many unicellular microorganisms play in the carbon cycle?

They are decomposers.

Why are pyramids of numbers and pyramids of biomass usually pyramid-shaped?

The amount of energy in organisms in a food web decreases as you go up the trophic levels.

Define 'species'.

A group of organisms that are able to reproduce to give offspring that are also able to reproduce.

What is the key difference between inherited and environmental variation?

Inherited variation comes from parents, while environmental variation is due to environmental factors.

What are biotic factors?

The activities of other organisms, such as competition, predation, and disease.

What are abiotic factors?

Non-living physical factors such as the amount of sunlight.

Define 'ecosystem'.

All the organisms and physical environmental factors in an area.

What is contained in chromosomes?

A long molecule of DNA.

What do genes contain?

Genetic information

What is adaptation?

Characteristics that allow animals and plants to survive in their habitat.

What is natural selection?

The process where, over time, beneficial inherited variations become more common in a population because they allow individuals to survive and reproduce better.

Name four causes of endangerment or extinction of species.

Changes in physical environmental factors, competition from other organisms, disease, and human activities.

List four ways to preserve biodiversity (the number of species).

Protecting areas, setting up nature reserves, setting up breeding programs in zoos, banning hunting/collecting, and setting up gene banks.

Why should we preserve biodiversity?

Organisms depend on one another, we won't be able to use organisms if they become extinct, and biodiverse areas recover better from natural disasters.

Write the word equation for photosynthesis.

Carbon dioxide + water -> glucose + oxygen

How are roots adapted to absorb water?

They are branched and spread out; they have root hair cells with a large surface area.

What mineral salts do plants need, and why?

Nitrates (to make proteins) and magnesium salts (to make chlorophyll).

How does carbon dioxide enter leaves?

Through stomata

Where does most photosynthesis happen?

In the palisade cells near the upper surface of leaves.

What is the role of chlorophyll?

A green chemical that absorbs energy transferred by light and uses it to power photosynthesis.

Write the word equation for aerobic respiration.

Glucose + oxygen -> carbon dioxide + water (+ energy)

What is ATP?

Molecules that store energy for a cell until it is needed; energy is transferred from glucose to ATP during respiration.

Name three uses of glucose in plants.

Respiration, making energy stores (e.g., starch), and making new materials for growth (e.g., cellulose, lipids, proteins).

What is sustainable development?

Developing the things we need without destroying habitats.

What are some problems caused by clearing land of hedges and trees in farming?

Destroys habitats; lack of roots can cause soil erosion.

What are some problems caused by pesticide use in farming?

Can kill useful organisms as well as pests; damages food webs.

What are some problems caused by fertilizer use in farming?

Can wash into streams and rivers and cause pollution, killing organisms in the water.

What are some problems caused by planting huge areas of a single variety of plant?

Reduces biodiversity.

What is selective breeding?

Choosing a plant with certain characteristics and breeding from it, then breeding from offspring with the best of those characteristics.

What is cross-breeding?

Breeding two different varieties together to try to produce offspring with characteristics from both varieties.

List three problems associated with burning fossil fuels.

Acid rain from sulfur dioxide, increase in carbon dioxide levels (greenhouse effect), and soot dirtying buildings/damaging health.

What is biomagnification?

The increase in toxin levels in large animals as they eat lots of smaller animals containing those toxins.

What are some problems with non-biodegradable polymer waste?

Causes pollution problems and dangers to animals for years.

List three solutions to environmental problems caused by materials.

Removal of sulfur from fuels, reduction in fossil fuel use (more renewables), control of hazardous waste, and use of biodegradable polymers.

List four benefits of recycling materials.

Reduces landfill use, reduces fossil fuel need, reduces pollution from manufacturing, and saves raw material resources.

Give examples of materials that can be recycled.

Metals, glass, polymers, paper, and concrete.

What happens in an exothermic reaction?

Energy is transferred into the surroundings, increasing the temperature around them.

What happens in an endothermic reaction?

Energy is transferred from the surroundings, decreasing the temperature around them.

What is peer review?

Scientists check other scientists' papers to validate conclusions, originality, and experimental design.

What is a chemical reaction?

A process in which new substances are made.

What causes gas pressure?

The force of the particles hitting the walls of the container.

How can you increase gas pressure?

Increase temperature, increase the number of particles, or decrease the volume of the container.

What is produced when metals react with water?

A metal hydroxide and hydrogen.

What is produced when metals react with dilute acids?

A salt and hydrogen.

What is oxidation?

The gain of oxygen.

What is reduction?

The loss of oxygen.

What is a redox reaction?

When oxidation and reduction occur at the same time.

What particles are present in the nucleus of an atom?

Neutrons and protons.

What do hydrocarbons contain?

Hydrogen and carbon only

What are the products of complete combustion of a hydrocarbon?

Carbon dioxide and water

What is the test for oxygen?

It relights a glowing splint.

How can the rate of a reaction be increased?

Increased temperature, increased concentration of a reactant, and increased surface area of a reactant.

What occurs during a displacement reaction?

A more reactive metal takes the place of a less reactive metal in a compound.

What are ores?

Rocks in the Earth's crust containing metals as compounds called minerals.

How are metals extracted from their ores?

Metals from zinc downwards can be extracted by heating with carbon. Metals above zinc need electrolysis.

What kind of field is a space where a non-contact force has an effect?

Force field

What is gravitational field strength (g) on Earth?

Approximately 10 N/kg.

What is static electricity?

The buildup of electric charge on the surface of an object.

How is current measured in an electric circuit?

Using an ammeter connected in series

How is voltage measured in an electric circuit?

Using a voltmeter connected in parallel

What is resistance?

A way of saying how easy or difficult it is for an electric current to flow through a component.

List three factors that the resistance of a wire depends on.

The material, its length, and its thickness.

What is an electromagnet?

A coil of wire with an electric current flowing through it; it is only magnetic while the current is flowing.

How can you make an electromagnet stronger?

Increase the number of coils, increase the size of the current, or use an iron core.

What is the motor effect?

If a wire carrying a current crosses a magnetic field, the wire will experience a force.

How can the speed of a motor be increased?

Increase the size of the current, increase the strength of the magnetic field, or increase the number of turns of wire on the coil.

What happens to an object moving at a constant speed?

The forces on it are balanced.

What happens when an object reaches its terminal velocity?

Air resistance balances the weight, and the object cannot fall any faster.

What is the formula for speed?

Distance / time

How is the steepness of a line related to an object or person's movement?

The steeper the line the faster the object or person is moving

What does the gradient of a line on a distance-time graph represent?

The speed that the object is moving.

What is a pivot also known as?

Fulcrum

What is a turning force called?

A moment

What is the formula for a moment?

Force × perpendicular distance from the pivot.

When is an object balanced?

When the anticlockwise moment is equal to the clockwise moment.

Name three simple machines.

Levers, ramps, and pulleys.

What is work done?

Energy transferred when a force moves through a distance.

What is the law of conservation of energy?

Energy cannot be created or destroyed, only transformed.