eQuizShow

Revision challenge

Biology

Question: Name 3 health problems people who are underweight are likely to experience.
Answer: 1. poor immune system

2. lack of energy to do things

3. likely to suffer from a lack of vitamins or minerals

Question: Give an example of a food chain, using the terms producer, primary consumer, secondary consumer, tertiary consumer, herbivore, omnivore, carnivore to describe each stage.
Answer: One example:

Acacia tree -> giraffe -> lion

producer - primary - secondary

Question: What is bioaccumulation?
Answer: When some chemicals are absorbed by a consumer and then this is passed on through the food chain and the chemicals are passed on to them. This carries on through the food chain, accumulating the chemical.

Question: Compare the problems of being overweight and being underweight
Answer: Underweight: poor immune system, lack of energy, lack of vitamins and minerals

Overweight: heart disease, stroke, diabetes, some cancers

Question: DDT is an insecticide that was once used to kill insects. It is no longer used, as it killed many fish- eating birds. The fish fed on plankton, which absorbed the insecticide from rivers. Draw a food chain to show this and explain how the insecticide killed the birds but not the fish.
Answer: plankton - fish - fish eating birds

Insecticide runs into river and is taken up by plankton. DDT accumulates in fish when they eat the plankton. One fish eats a lot of plankton, but not enough to cause death. DDT accumulates in birds when they eat the fish. One bird eats many fish. DDT level is now high/ concentrates that it causes death in the bird.

Chemistry

Question: magnesium + chlorine -->
Answer: magnesium chloride

Question: Does the reaction happen? If yes, what are the products?

fluorine + magnesium chloride -->

Answer: magnesium fluoride + chlorine

Question: You get a sample of rock salt that you need to obtain the salt from. What methods would you use?
Answer: Filtration

Evaporation

(crystallisation)

Question: What is a reduction reaction? State an example (writing a word equation) and why it is useful
Answer: Removal of oxygen atoms. Example: iron oxide + carbon --> carbon dioxide + iron

Question: Emma places a piece of potassium in water. What will she observe? Why?
Answer: The potassium piece fizzes, a gas is produced. The gas is hydrogen (potassium + water --> potassium hydroxide + hydrogen). Potassium hydroxide dissolves in water, which makes the solution alkaline

Physics

Question: How do you work out the average speed of a moving object?
Answer: A.S. = total distance/ total time taken

Question: What does a horizontal line show on a distance- time graph?
Answer: That the object is stationary.

Question: Define potential difference? and how do we measure it?
Answer: A cell or battery provides the push to make charges move. The push is called a potential difference. The p.d. across a cell tells you about the size of the force on the charges.

Question: Unscramble the words below and pair them up. Explain why you have chosen to pair them that way.

notpro, oneturn, iviespot, gianteve, laterun, centrelo

Answer: Proton - positive

Neutron - neutral

Positive - proton

Neutral - neutron

Electron - negative

Question: State what happens to the total current as you add more bulbs in a parallel circuit.
Answer: The current increases.

Challenge

Question: How do you test for starch?
Answer: To test for starch you use iodine solution. Iodine solution is an orange-yellow liquid.

1. Add a few drops of iodine solution to the food solution

If the solution turns a dark blue-black colour, the food contains starch

Question: How do you test for lipids?
Answer: To test for lipids in a solid piece of food, you use a piece of filter paper.

1. Rub some of the food onto a piece of filter paper

2. Hold the paper up to the light. If the paper has gone translucent, the food contains lipids.

Question: Describe the trends in alkali metals and halogens
Answer:

As we go down group 1, the reactivity increases. As we go down group 7, the reactivity decreases.

Question: A runner runs 100 meters in 12.5 seconds. Calculate her average speed.
Answer: speed = distance/time

speed = 100/ 12.5

speed = 8 m/s

Question: Describe how a paper chromatogram is obtained. Explain how the coloured substances separate.
Answer:

A horizontal line is drawn on filter paper, using a pencil. An ink dot is placed on the pencil line, of the mixture we will separate.

The strip is placed into a solvent which is absorbed by the paper. As the solvent moves up, the coloured substances separate.

This happens as they have different solubility in the solvent and different attraction to the paper.

Super challenge

Question: You are investigating how magnesium and copper react with hydrochloric acid. You add a piece of the metal is the acid. How would you make the investigation fair?
Answer:

Same mass (or size) of metal

Same volume of the acid

Question: Write a balanced equation for the reaction of sodium (Na) with water.

HINT: The products are sodium hydroxide and hydrogen.

Answer: The products are sodium hydroxide (NaOH) and hydrogen.

2Na + 2H2O -> 2NaOH + H2

Question: Explain why it is important to eat a fibre - rich diet.
Answer: Adds bulk to the food which muscles push against to force the food along the gut. Fibre- rich foods also prevent constipation.

Question: Where is bile made? What is the role of bile?
Answer: Bile is made in the liver. Bile breaks down lipids into smaller droplets which make it easier for lipase enzymes to break down.

Question: Use the speed equation to explain how a speed camera calculates a cars speed.

HINT: Think about distance travelled, position of the car and speed equation.

Answer: Lines are painted on the road a set distance apart. The camera takes a photograph of the car on the road. The camera takes a photograph of the car a short time later. From the position of the car, the camera can work out how far the car has travelled. The camera can use the time between the photographs to find the time using the equation: speed= distance/time. The camera uses the info from the two photographs to calculate the speed. If the car is travelling faster than the speed limit, it will travel to far in the time between the photographs.