Waves, Specific heat capacity, Reactivity series, Acids and bases, Disease and Evolution

Question 1

Describe natural selection…

Answer 1

Natural selection states that offspring will show variation in their characteristics and some variations will be better adapted to the environment than others. The limited resources will cause competition between individuals and those who have variations will be more likely to survive as they are better adapted and those who are not will die. Individuals that survive may breed and so many pass their variations on to their offspring.

Question 2

What did Darwin realise which led to the theory of evolution?

Answer 2

Darwin realised that if the environment changes, the different variations may be better suited to the new competition. Also, he realised that the range of that range of variation in characteristics of the population will gradually change over generations, which i evolution.

Question 3

According to Darwin’s theory, what happens if the environment changes too rapidly?

Answer 3

No individuals have time to adapt (which will help them survive) and they will all die out and therefore the specie may become extinct.

Question 4

Give an example of new evidence for Darwin’s theory…

Answer 4

Warfarin is a chemical that was used to poison rates in the 1940s/50s and when it was first used most rats died from it. But within ten years most rats were resistant to warfarin, they had adapted in order to survive.

Question 5

What are the 4 ways to neutralise an acid?

Answer 5

1. acid + base = salt + water
2. acid + metal = salt + hydrogen
3. acid + metaloxide = salt + water
4. acid + metal carbonate = salt + water + carbon dioxide

Question 6

What is a compound?

Answer 6

More than one element together

Question 7

What are bases? What are alkalis?

Answer 7

Bases are compounds that can neutralise acids, and alkalis are those bases that that are soluble in water, such as the hydroxides of group 1 metals.

Question 8

What are the two similarities between transverse waves and longitudinal waves?

Answer 8

1. Can reflect.

2. Waves carry energy from place to place.

Question 9

What are the three most reactive elements in the reactivity series?

Answer 9

1. Potassium
2. Sodium
3. Lithium

Question 10

Which non metal is ranked higher in the reactivity series, carbon or Hydrogen?

Answer 10

Carbon.

Question 11

HCL+ Na0H =
Hydrochloric + Sodium
acid Hydroxide

Answer 11

NaCL + H(small2)0
Sodium + water
chloride

Question 12

2HCL + mg =
Hydrochloric + magnesium
acid

Answer 12

MgCL(small 2) + H(small2)
Magnesium + Hydrogen
chloride

Question 13

List the reactivity series…

Answer 13

Potassium 
Sodium 
Lithium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron 
Tin 
Lead
Hydrogen
Copper 
Silver 
Gold

Question 14

What are the four pathogens that cause disease? Give examples of the diseases the cause…

Answer 14

1. Bacteria (cholera, food poisoning and TB)
2. Viruses (influenza, measles and AIDS)
3. Fungi (athlete’s foot)
4. Protoctisits (malaria)

Question 15

How is AIDS spread?

Answer 15

By body fluids (blood shared on syringe or during sexual intercourse)

Question 16

H(small 2)SO(small4) + KO =

Sulphuric acid + Potassium oxide

Answer 16

KSO(small 4) + H(small 2) O

Potassium sulphate + water

Question 17

H(small 2)NO(small3) + LiCO(small 3) =

Nitric acid + carbonate

Answer 17

LiNO(small 3) + H(small2)O + CO(small 2)

Lithium Nitrate + water + carbonate

Question 18

How do transverse waves particles move?

Answer 18

Particles move at right angles to the direction the wave is moving.

Question 19

What do longitudinal wave particles do?

Answer 19

The air particles are pushed together and move back and forth and have vibrations that are parallel to the direction of energy transfer.

Question 20

An example of a longitudinal wave…

Answer 20

Sound waves

Question 21

An example of a transverse wave…

Answer 21

Water waves

Question 22

What happens when water waves go from deep to shallow water?

Answer 22

The energy spreads itself out more and its speed slows down.

Question 23

What is a genetic disease?

Answer 23

A disease which is caused by an abnormality in someone’s DNA, which are passed on by Autosomal recessive inheritance.

Question 24

What can white blood cells do?

Answer 24

Ingest pathogens (the cause of the disease and therefore destroy them)
Produce antibodies which neutralize pathogens such as bacteria and viruses.
Produce antitoxins that counteract the toxins released by pathogens.

Question 25

What is made in the stomach to kill harmful bacteria?

Answer 25

Hydrochloric acid

Question 26

What happens to the bacteria that can survive acid conditions in the stomach?

Answer 26

This bacteria can later be identified and killed with antibiotics.

Question 27

What enzyme does blood, tears, mucus and saliva contain? What does it do?

Answer 27

Lysozyme. It breaks down cells walls of bacteria and destroys them.

Question 28

How does the body defend itself when the skin is cut?

Answer 28

The blood begins to clot in order to prevent the entry of pathogens.

Question 29

How do diseases spread:

Answer 29

In air,
through contact with animals, 
through contaminated foods, 
through touch (direct or indirect, like athlete's foot),
in water.

Question 30

A cold is a virus can antibiotics help?

Answer 30

No, because a cold is a virus and antibiotics only work on bacterial infections.