Year 8 Science Revision Flashcards

Flashcards covering various topics from the Year 8 Science curriculum, focusing on key concepts, definitions, and processes discussed in the provided notes. Topics include nutrition, digestion, respiration, kingdoms, reproduction, atomic theory, combustion, metals, fluids, light, and energy transfer.

Why do we need to eat a wide variety of foods?

To get all the food substances that we need for a balanced diet.

Name three nutrients that provide raw materials for making other substances the body needs.

Carbohydrates, proteins, fats and oils (lipids), vitamins and minerals.

What are carbohydrates needed for?

Energy (in respiration).

What are proteins needed for?

Growth and repair (building new substances).

Give an example of a good source of Vitamin C.

Fruits and vegetables (e.g., oranges).

Why is fiber important?

For health, helps to stop constipation.

Why is water important for health?

Water dissolves substances and fills up cells.

What happens when starch reacts with iodine solution?

It turns a blue-black colour.

What unit is energy in food measured in?

Kilojoules (kJ).

Name three factors that the amount of energy a person needs in a day depends on.

Levels of activity, age, and whether the person is a girl or a boy.

What can eating too much fat cause?

Heart disease and can make people overweight.

What is the term for being very overweight?

Obese.

What can result from eating too little?

Starvation and weakness.

What are starvation and obesity both forms of?

Malnutrition.

What deficiency causes scurvy?

Lack of vitamin C.

What does digestion turn large insoluble substances into?

Small soluble ones.

What do many of the organs of the digestive system produce?

Enzymes (substances that are catalysts and help speed up food digestion).

Where is food digested?

In the gut.

What features of the small intestine help absorb digested food?

The wall of the small intestine is folded and covered with villi. The cells have microvilli.

Why is it easy for small molecules to diffuse out of the small intestine and into the blood?

The wall of the small intestine is only one cell thick.

Where are the digested food molecules carried?

In the blood plasma.

What is the surface area to volume ratio?

Its surface area divided by its volume.

Why do cells need large surface area to volume ratios?

To get enough of the substances they need from the surroundings.

What do all living cells do to release energy?

Respire.

Give an example of what organisms need energy for.

Making new substances, moving.

What is the word equation for aerobic respiration?

glucose + oxygen → carbon dioxide + water

What can carbon dioxide be detected using?

Limewater (which it turns cloudy) or an indicator (such as hydrogen carbonate) because it is acidic.

Does anaerobic respiration require oxygen?

No.

What does anaerobic respiration cause in humans?

Muscles to tire quickly.

Where is a lot of the lactic acid from anaerobic respiration converted back to glucose?

The liver.

Does anaerobic respiration release more or less energy than aerobic respiration?

Less energy.

What is EPOC?

Excess post-exercise oxygen consumption (or ‘oxygen debt’)

Give three examples of organs that different organisms use for gas exchange.

Gills in fish, lungs in humans and stomata in plants.

What increases when you exercise?

Breathing rate and pulse rate.

What muscles are involved in breathing?

Muscles in the diaphragm and attached to the ribs.

What happens to the diaphragm during inhalation?

Contracts and moves downwards.

What happens to the ribs during inhalation?

Rib muscles contract and lift ribs up and outwards.

What happens to the volume of the chest during inhalation?

Volume of the chest increases.

What happens to the pressure in the lungs during inhalation?

Decreases.

What happens to the diaphragm during exhalation?

Relaxes and moves upwards.

What happens to the ribs during exhalation?

Rib muscles relax and move ribs down and inwards.

What happens to the volume of the chest during exhalation?

Volume of the chest decreases.

What happens to the pressure in the lungs during exhalation?

Increases.

What happens to the lungs during inhalation?

Lungs expand.

What happens to the lungs during exhalation?

Lungs get smaller.

What is ventilation?

The movement of air into and out of the lungs.

What is vital capacity?

The maximum amount of air you can exhale after taking as much air into your lungs as you can.

What is tidal volume?

The volume of air in each breath.

What chemical in cigarette smoke makes arteries narrower and causes heart disease?

Nicotine.

What chemical in cigarette smoke can cause cancer, coat the lungs, and cause emphysema?

Tar.

What chemical in cigarette smoke stops red blood cells carrying so much oxygen?

Carbon monoxide.

What does the high temperature of cigarette smoke cause?

Stops cilia working so lungs are not cleaned and mucus collects.

How do you calculate range?

Highest value – lowest value.

How do you calculate mean?

Total of all values / number of values.

What are the last two groups used to define each species scientific name?

Genus and species.

Name three characteristics of plants.

Plants have green leaves, have cell walls made of cellulose and can photosynthesise.

Name the four main groups of the plant kingdom .

Flowering plants, conifers, ferns and mosses.

Name the groups vertebrates are divided into.

Mammals, reptiles, fish, amphibians and birds.

Give two examples of invertebrates.

Molluscs and arthropods.

What two groups do arthropods include?

Insects and arachnids.

What is biodiversity?

The range of species in an area.

Give three reasons why we should preserve biodiversity.

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

What is asexual reproduction in plants?

When one parent plant is able to produce offspring.

What are gametes?

Sex cells.

What is a zygote?

A fertilised egg cell.

What is the term for the differences in inherited characteristics?

Inherited variation.

Where are gametes produced in plants?

Reproductive organs inside flowers.

What is pollination?

The carrying of pollen from an anther to a stigma.

Where does a pollen grain grow a pollen tube to once on the stigma?

Enters the ovule containing an egg cell.

What joins with the nucleus inside the egg cell to form a zygote?

The nucleus from the male gamete inside the pollen grain.

What does the zygote grow into?

An embryo.

What resources are needed for seeds to germinate?

Water, oxygen and warmth (WOW).

What grows first from a germinating seed?

The root.

What is the mass of material produced called?

Biomass.

What nutrients are called mineral salts needed by a growing plant?

Light, air, water, warmth and nutrients.

What organelle does respiration happen in?

Mitochondria.

What is a quadrat used for?

Estimating plant populations in an area.

What did Dalton's Atomic Theory state about atoms?

All matter is made up of tiny particles called atoms, atoms are indestructible, and cannot be created, or destroyed, the atoms in an element are all identical, in compounds, each atom of an element is always joined to a fixed number of atoms of the other elements, during chemical reactions, atoms rearrange, to make new substances.

Name four signs of a chemical reaction.

Colour change, a gas being produced, a solid forming in a solution and an increase/decrease in temperature.

What happens to the mass during a physical change?

No atoms are lost or gained during a physical change and so the mass of the substance stays the same.

In chemical formulas, what does a substance tells the number of?

Tells you the number of atoms of each element.

What are some common properties of metals?

high melting points (most are solids), strong, malleable and ductile, shiny (when polished), good conductors of heat and electricity.

What are some common properties of non-metals?

low melting point , brittle (when solid), not shiny, poor conductors of heat and electricity.

Name two types of physical properties.

Melting point, boiling point, density.

What are elements ordered by in today's periodic table?

In order of atomic number (the number of particles called protons in an atom).

Metal oxides form what types of solutions?

Alkaline solutions.

Non-metal oxides form what types of solutions?

Acidic solutions.

What is the word equation for a neutralisation reaction?

acid + base → salt + water

What elements are hydrocarbons made of?

Carbon and hydrogen only.

Is combustion endothermic or exothermic?

Exothermic.

Why is combustion also an oxidation reaction?

Because the substances react with oxygen.

What gas turns limewater ‘milky’?

Carbon dioxide.

What gas burns with a squeaky pop?

Hydrogen.

What colour does water turn blue cobalt chloride?

Pink.

What colour does water turn anhydrous copper sulfate?

Blue.

What two products are released when a hydrocarbon combusts?

Carbon dioxide and water vapour.

What did scientists name the substance given out to air as a substance burnt, before oxygen was discovered?

Phlogiston.

How do water extinguishers put out fires?

Remove heat.

How do powder and carbon dioxide extinguishers put out fires?

Exclude oxygen.

Why should oil fires not be treated with water?

The water sinks through the oil, which heats up and causes the water to evaporate. This causes the oil to ‘spit’ and can spread the fire.