Year 9 Science Review Flashcards

Comprehensive practice flashcards covering Year 9 Science concepts, including energy and electricity, homeostasis, nervous and endocrine systems, infectious and non-infectious diseases, chemical bonding, organic compounds, and polymers.

What is the Law of Conservation of Energy?

Energy cannot be created or destroyed, only transferred or transformed.

What is voltage?

The energy transferred per unit of charge.

What is current?

The flow of electric charge.

What unit measures current?

Amperes (A).

What unit measures voltage?

Volts (V).

What unit measures resistance?

Ohms ($\Omega$).

What is Ohm's Law?

$$V = I \times R$$

How many paths are there in a series circuit?

One path.

How many paths are there in a parallel circuit?

Multiple paths.

What happens if one component breaks in a series circuit?

The entire circuit stops working.

What is homeostasis?

Maintaining a stable internal environment.

What is a stimulus?

A change in the environment.

What is a response?

A reaction to a stimulus.

What is a receptor?

A cell or organ that detects a stimulus.

What is an effector?

A muscle or gland that carries out a response.

Which system is faster: nervous or endocrine?

Nervous system.

How does the nervous system send messages?

Electrical impulses through nerves.

How does the endocrine system send messages?

Hormones in the bloodstream.

What happens when you're too hot?

You sweat and blood vessels widen.

What happens when you're too cold?

You shiver.

What is a pathogen?

A microorganism that causes disease.

Name the four types of pathogens.

Bacteria, viruses, fungi, protozoa.

Give an example of a bacterial disease.

Tuberculosis.

Give an example of a viral disease.

Influenza (flu).

Give an example of a fungal disease.

Athlete's foot.

Give an example of a protozoan disease.

Malaria.

What is a vector?

An organism that carries a pathogen.

How is malaria spread?

By mosquitoes.

What is the body's first line of defence?

Skin.

What are white blood cells?

Cells that defend the body against pathogens.

What are antibodies?

Proteins that target specific pathogens.

What are antitoxins?

Chemicals that neutralise toxins.

What is immunity?

Protection against a disease.

What is a vaccine?

A preparation that stimulates immunity.

What are memory cells?

Cells that remember pathogens.

What is herd immunity?

Community protection when many people are immune.

What is a non-infectious disease?

A disease that cannot spread from person to person.

Give an example of a non-infectious disease.

Type 2 diabetes.

What is cardiovascular disease?

Disease affecting the heart and blood vessels.

Name one risk factor for heart disease.

Smoking.

How does exercise improve health?

It reduces disease risk and improves fitness.

Why is prevention important?

It reduces the chance of developing disease.

What is an ion?

A charged atom.

What is a cation?

A positively charged ion.

What is an anion?

A negatively charged ion.

How is a positive ion formed?

By losing electrons.

How is a negative ion formed?

By gaining electrons.

What is ionic bonding?

Attraction between oppositely charged ions.

What is covalent bonding?

Sharing electrons.

What is metallic bonding?

Attraction between metal ions and delocalised electrons.

Why do metals conduct electricity?

Because they have free-moving electrons.

What is a hydrocarbon?

A compound made only of carbon and hydrogen.

What is an alkane?

A saturated hydrocarbon with only single bonds.

What is methane's formula?

$$CH_4$$

What is crude oil?

A mixture of hydrocarbons.

What process separates crude oil?

Fractional distillation.

What is combustion?

Burning in oxygen.

What are the products of complete combustion?

Carbon dioxide and water.

What poisonous gas is produced in incomplete combustion?

Carbon monoxide.

What is a polymer?

A large molecule made from repeating monomers.

What is a monomer?

A small molecule that joins with others.

What is polymerisation?

The process of joining monomers together.

Give an example of a synthetic polymer.

Nylon.

Give an example of a natural polymer.

Starch.

What are microplastics?

Tiny plastic particles less than $5\,\text{mm}$ in size.

Why are microplastics harmful?

They pollute ecosystems and enter food chains.

What is recycling?

Turning waste into new products.

What is one advantage of plastics?

They are durable and lightweight.

What is one disadvantage of plastics?

They can cause environmental pollution.