B1 Topic 1 Variation

Question 1

Plants

Answer 1

Contain chlorophyll and are autotrophs. (Make their own food through photosynthesis). They are multicellular and have ridged cell walls.

Question 2

Animals

Answer 2

They are heterotrophs (move around to find food). They are multicellular but don’t have cell walls or chlorophyll.

Question 3

Fungi

Answer 3

They are saprophytes so they feed off dead organisms and decaying material. They’re multicellular, have a cell wall but no chlorophyll.

Question 4

Protoctists

Answer 4

They’re unicellular (single celled) but have no nucleus.

Question 5

Prokaryotes

Answer 5

They’re unicellular but they don’t have a nucleus.

Question 6

Viruses

Answer 6

They are classed as non living so they are in no kingdom.

Question 7

Phylum Chordata

Answer 7

Is made up of all animals that have a supporting rod like structure that goes up the back of the body.

Question 8

Vertebrates and invertebrates

Answer 8

Vertebrates have a backbone and an internal skeleton. Invertebrates don’t.

Question 9

Vertebrae groups

Answer 9

Fish, amphibians, reptiles, birds, mammals. They are divided by how they absorb oxygen. How they reproduce. How they regulate their internal body temperature.

Question 10

Classification

Answer 10

It is organising living organisms into groups. They classify them on how closely related they are to each other. The five kingdoms are plants, animals, fungi, protoctists, prokaryotes.

Question 11

Variation

Answer 11

It is the differences within a species.

Question 12

Genetic variation

Answer 12

Different genes cause genetic variation. The combining of genes from two parents causes genetic variation because no two of the same species are genetically identical.

Question 13

Environmental variation

Answer 13

Environmental variation is caused by the environment that organisms live and grow in. E.g. Getting a sun tan due to the sun.
The factors it includes are diet, exercise, temperature, light level, amount of water etc.

Question 14

Continuous and discontinuous variation

Answer 14

Continuous variation is when the individuals in a population vary within a range. Discontinuous variation is when there are two or more distinct categories.

Question 15

Extreme environments

Answer 15

Organisms have to adapt to live in the deep sea. E.g larger eyes. In volcanic vents bacteria uses chemical energy to make it’s food. (Chemosynthesis). Polar bears have a compact shape to give them a small surface area therefore less heat is lost. White fur for camouflage and a thick white coat for keeping heat.

Question 16

Natural selection

Answer 16

It is the survival of the fittest. Evolution is the slow and continuous change of organisms from generations.

Question 17

Evidence for evolution

Answer 17

DNA research - shared common ancestors. Closely related species diverged more recently. Caused by gradual changes in DNA. Organisms that have diverged away from each other have similar DNA.
Resistant organisms - The poison warfarin was used to kill rats. But a caper train gene gives it resistance.

Question 18

Validating evidence

Answer 18

Through science journals and peer review. Scientific conferences.

Question 19

Speciation and genes

Answer 19

Speciation is the development of a new species. It occurs when the same species become so different they can no longer breed. For this too happen the species have to be separated into two different environments . Once they have adapted the new species will develop.

Question 20

Genes

Answer 20

The nucleus contains the genetic material in the form of chromosomes. Humans have 23 pairs. Chromosomes are long lengths of DNA coiled up, a gene is a short section of the DNA. Different genes control the development of different characteristics.

Question 21

Allele

Answer 21

An allele is a different version of the same gene.

Question 22

Cystic fibrosis

Answer 22

It is caused by a recessive allele. It is a genetic disorder of the cell membranes. It results in the body making lots of a thick mucus in the air passages and pancreas. The symptoms are breathing difficulties, lung infections, malnutrition and fertility problems.

Question 23

What is the allele that causes cystic fibrosis?

Answer 23

The allele which causes cystic fibrosis is a recessive allele (f). As it is recessive it means that people with only one copy of the allele won’t have it but will be a carrier. For offspring to inherit it their parents must both be carriers or sufferers.

Question 24

Sickle cell anaemia

Answer 24

This is also caused by a recessive allele. It is a genetic disorder of different shaped red blood cells. These blood cells get stuck in capillaries, which deprives body cells of oxygen. Symptoms are tiredness, painful joints and muscles, fever and anaemia. It is caused by inheriting two recessive alleles (a). A normal allele is represented with an (A).

Question 25

How do polar bears adapt to the environment?

Answer 25

Thick blubber acts as an insulating layer. Two layers of white fur so it’s
less easy to see, repels water and keeps bear dry. Hair follicles are hollow to trap warm air. Black skin absorbs heat. Wide surface area of paws spreads out the weight on the ice.

Question 26

How does the Pompeii worm adapt to the environment?

Answer 26

It can adapt to pressures 200x the amount on the surface. It has tentacles to feel for food instead of eyes, it is dark. It undergoes chemosynthesis as there is no light. A layer of surface bacteria allow it to handle temperature changes of 40-90°C.