B1 Topic 1 - Variation

Question 0

What are the main characteristics of plants?

Answer 0

Contain chlorophyll
Are autotrophs (produce their own food by photosynthesis)
Are multicellular
Cells have cells walls which support cells

Question 1

What are the five kingdoms that all living things are divided into?

Answer 1

Animals, plants, fungi, protoctists and prokaryotes

Question 2

What are the main characteristics of animals?

Answer 2

Heterotrophs (can’t make their own food)
Multicellular
Don’t have cell walls or chlorophyll

Question 3

What are the main characteristics of fungi?

Answer 3

Saprophytes (eat dead organisms and decaying material)
Multicellular
Have cell walls but no chlorophyll

Question 4

What are the main characteristics of protoctists?

Answer 4

Unicellular

Have nuclei

Question 5

What are the main characteristics of prokaryotes?

Answer 5

Unicellular

No nucleus

Question 6

Briefly explain the binomial system.

Answer 6

Gives all living organisms a two part name

First refers to the genus and the second refers to the species

Question 7

Name some advantages of the binomial system.

Answer 7

Identifying species
Studying species
Conserving species
Targeting conservation efforts

Question 8

What are the two causes of variation?

Answer 8

Genes and the environment

Question 9

Define continuous variation.

Give some examples.

Answer 9

When the variable being recorded has no distinct categories and is more like a range.
Height, weight, hand span

Question 10

Define discontinuous variation.

Give some examples.

Answer 10

When there are two or more distinct categories and no intermediates.
Blood type, hair colour, eye colour

Question 11

How are polar bears adapted to live in the Arctic?

Answer 11

Compact bodies so less heat loss
Thick layer of blubber for insulation
Thick coat traps layers of air
Greasy fur repels water to prevent cooling by evaporation
Big feet to spread weight on snow which stops them from sinking
White fur to match surroundings - snow…

Question 12

Define evolution.

Answer 12

A slow and continuous change of organisms from one generation to the next.

Question 13

Briefly explain natural selection.

Answer 13

1. Individuals not all the same due to mutations.
2. Populations have to compete for limited resources e.g. Food or water.
3. Individuals with better characteristics are more likely to survive long enough to reproduce and pass on these characteristics.
4. Offspring of this individual are better adapted and can pass it on to their offspring as well.
5. Some individuals are less well adapted and are therefore less likely to pass on their genes.
6. Over time, there are more better adapted individuals compared with the lesser adapted ones.
7. EVOLUTION

Question 14

Define speciation.

Answer 14

Speciation is when a population of the same species become so different that they can no longer produce fertile offspring.

Question 15

Explain how speciation occurs?

Answer 15

One part of a population becomes isolated from the rest, maybe by a physical barrier. If the conditions on each side happen to be different, each group will evolve to suit its own area. After millions of years, the two populations will have adapted so much that they will no longer be able to have fertile offspring.

Question 16

What is hybrid?

Answer 16

When two different species interbreed.

Question 17

What is a species?

Answer 17

A species is a group of organisms with similar characteristics that can breed to make fertile offspring.

Question 18

List the different classifications for organisms, starting with ‘Kingdom’.

Answer 18

Kingdom, Phylum, Class, Order, Family, Genus, Species

King Philip Came Over For Good Soup

Question 19

What is a hybrid?

Answer 19

A hybrid is the offspring of two organisms that come from different species. The hybrid is usually infertile.

Question 20

Why aren’t viruses classified in the binomial system?

Answer 20

Viruses don’t have all the characteristics of a living organism and so scientists are still debating as to whether they are alive or not.

Question 21

Describe the main characteristics of the phylum a Chordata.

Answer 21

All the species in this phylum are vertebrates, meaning that they have a spine to support their body structure.

Question 22

State some methods that organisms:

• Absorb oxygen
• Reproduction
• Thermoregulation

Answer 22

Oxygen:
Inhaling through lungs, absorption through gills, diffusion through skin

Reproduction:
External fertilisation (fish), internal fertilisation (mammals), oviparous (lay eggs), viviparous (live young)

Thermoregulation:
Homeothermic (warm-blooded, generate own heat), poikilothermic (cold-blooded, use sun or other sources to warm up the blood)

Question 23

Explain evolution with respect to variation, over-reproduction, struggle for existence, survival, organisms inheriting characteristics from their parents and changes in the proportion of individuals which are better adapted to their environment.

Answer 23

Even organisms from the same species have slight variations due to small mutations in their DNA. Occasionally, these mutations may give an organism a better chance of surviving until it reaches reproductive maturity.

This organism will then have a greater chance of mating to have many offspring. By having many offspring, more of the babies will also carry the beneficial adaptation and a higher number of those better adapted will survive long enough to pass the genes down to the next generation.

As well as the better adapted organisms increasing in numbers, the weaker organisms in that species will have their chances of survival lowered due to changes in environment that the better adapted organisms are better adapted to.

Eventually, after millions of years and generations, the proportion of organisms that are better adapted will greatly outnumber the original species until the old species becomes ‘extinct’.

Question 24

What is genetic variation?

Answer 24

Genetic variation is the difference in the alleles between individuals in a population or species.

Question 25

Define gene.

Answer 25

A section of DNA that codes for a characteristic.

Question 26

Define chromosome.

Answer 26

Chromosomes are long strand of genes, which are made up of DNA.

Question 27

Define dominant.

Answer 27

The dominant allele is the gene which actually controls the characteristic.

Question 28

Define recessive.

Answer 28

The allele which does not have any impact on the organism but that can still be passed on to its offspring.

Question 29

Define homozygous.

Answer 29

When the genotype a of an organism are the same.

E.g. hh or HH

Question 30

Define heterozygous.

Answer 30

When the genotypes of an individual are different.

E.g. Hh

Question 31

Define genotype.

Answer 31

The genotype of a characteristic in an organism are the genes that it has though not necessarily those that control the characteristic.

Question 32

Define phenotype.

Answer 32

Phenotype is the characteristic of an organism caused by its dominant allele.