Science - Biology

Question 1

What is variation?

Answer 1

The presence of differences between living things of the same species is called variation .

Question 2

Examples of genetic (inherited) variation

Answer 2

Blood group
Eye colour
Gender

Question 3

Examples of environmental variation

Answer 3

Broken leg
Accent
Scars
Tattoos

Question 4

Examples of variation that is both environmental and genetic (inherited)

Answer 4

Skin colour
IQ
Weight
Height
Eyesight

Question 5

Where are your genes found?

Answer 5

Genes are in every cell in your body that has a nucleus. In the cell there is a nucleus and in that nucleus holds your chromosomes. They contain your DNA which is where all of your genes are.

Question 6

What does DNA stand for?

Answer 6

deoxyribonucleic acid

Question 7

Who discovered DNA and when?

Answer 7

James Watson, Francis Crick and Rosalind Franklin in 1953

Question 8

Describe the structure of DNA:

Answer 8

DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. DNA is described as a double helix, each molecule of it contains two strands that bend around each other like a twisted ladder.

Question 9

What is an allele?

Answer 9

Different forms of the same gene are called alleles.

Question 10

What is a dominant allele?

Answer 10

The type of allele that will always produce a characteristic in an organism are called dominant alleles.

Question 11

What is a recessive allele?

Answer 11

The type of allele that will only produce a characteristic in an organism if both alleles are the same is a recessive allele.

Question 12

What are punnet squares used for?

Answer 12

By carrying out a genetic cross scientists can predict what an offspring will look like. They use a punnet square to show what happens to the alleles in the genetic cross.

Question 13

How many chromosomes do we have?

Answer 13

23airs of chromosomes or 46 overall chromosomes.

Question 14

How many chromosomes do we get from each parent?

Answer 14

23 chromosomes from each parent

Question 15

What is a gamete and what does it do?

Answer 15

Gametes: sex cells, human egg and sperm cell.
When fertilisation happens the gametes fuse together to make a single cell called a zygote. The zygote has 46 chromosomes.

Question 16

What is a homozygous allele?

Answer 16

Homozygous alleles means the alleles in a matching pair are the same.
e.g if you have two yellow genes then they are homozygous genes.

Question 17

What is a heterozygous allele?

Answer 17

Heterozygous alleles means the alleles in a matching pair are different.
e.g
If you have a yellow and red gene then they would be heterozygous alleles.

Question 18

What is a genotype?

Answer 18

The allele pair for each characteristic is called the genotype. They are written in letters that are either capital or lower case.

e.g: RR, rr, Rr

Question 19

What is a phenotype?

Answer 19

The physical expression of an allele pair is the phenotype. It is written in words.

e.g: Red, Yellow

Question 20

What is a gene?

Answer 20

A sequence of nucleotides forming part of a chromosome, which determines your characteristics.

Question 21

How are dominant and recessive alleles shown?

Answer 21

Dominant=capital letter R

Recessive=lower case letter r

Question 22

Who is Gregor Mendel?

Answer 22

He is thought of as the father of genetics. He did many experiments to learn about genes and inheritance of genes.

Question 23

What is a genetically inherited disorder?

Answer 23

It is a condition passed from their parents to their offspring in their genes.

Question 24

What is cystic fibrosis?

Answer 24

It is a genetically inherited disorder which causes the sufferer to produce lots of thick sticky mucus which blocks air passages, making it difficult to breath. It can cause chest infections and difficulty in food being absorbed.

Question 25

Is the allele for cystic fibrosis recessive or dominant?

Answer 25

It is recessive, needs two genes.

Question 26

What is polydactyl ?

Answer 26

Polydactyl is a genetically inherited disorder that results in a child being born with extra digits on their hands or feet. These can be small stumps or soft tissue, or extra fingers/toes.

Question 27

Is the allele for polydactyl recessive or dominant?

Answer 27

It is dominant which means you only need one of the genes and you cant be a carrier.

Question 28

What is selective breeding?

Answer 28

Selective breeding is where individuals of the same species with desirable traits, are bred together to increase the chance of the offspring having the same desirable trait.

Question 29

What are the five main steps in selectively breeding an organism?

Answer 29

1) decide which characteristics of the species is most important
2) select parents that show high levels of this characteristic
3) breed these individuals
4) select the best offspring and breed again
5) repeat for many generations.

Question 30

What are the disadvantages of selective breeding?

Answer 30

Many suffer from health problems as a result of this breeding. Examples:
Sausage dogs are prone to spinal problems like intervertebral disk disease.

Question 31

Who is dolly the sheep?

Answer 31

She was the first organism that was cloned.

Question 32

What is genetic engineering?

Answer 32

In genetic engineering, genes from chromosomes of humans and other organisms can be cut out using enzymes and transferred to cells of other organisms.

Question 33

Examples of organisms that have been genetically engineered:

Answer 33

Glowing mice:

Jellyfish gene is put into mouse cells which make the mice glow in UV light.