B5.1-Inheritance

Question 1

What is a recessive allele?

Answer 1

An allele that is only expressed if you have two copies of the allele, one from each parent

Question 2

What are the advantages and disadvantages of asexual reproduction ?

Answer 2

Advantages: if an offspring is well adapted to the area it will share an identical set of characteristics It is faster since only one parent is needed Disadvantages: changes to biotic and abiotic factors may result in the whole species dying out

Question 3

Are all mutations harmful?

Answer 3

Not all mutations are harmful some mutations are neutral (neither benefit nor harm the organisms) Some can even be beneficial as conjugation in bacteria allows for antibiotics in plasmids to be transferred between cells

Question 5

What is the second stage of meiosis?

Answer 5

6. The chromosomes line up along the middle of each of the new cell 7. This time each chromosome is pulled in half. A single copy of each pair is pulled to opposite ends of the cell 8. The cell then divides into two. This results in four haploid cells that are genertically different

Question 6

What is asexual reproduction?

Answer 6

Asexual reproduction is when an organism reproduces itself without a mate. This produces a clone with the exact genetic makeup of the parent

Question 7

What is a gamete?

Answer 7

A gamete is a sex cell produced during sexual intercourse. It is a haploid cell since two gametes fuse to form a zygote (diploid cell).Examples are sperm and egg cells

Question 8

How many pairs of chromosomes does a human have?

Answer 8

A human has 23 pairs of chromosomes. 22 pairs are identical in appearance. The 23rd pair known as the sex chromosomes are different. Two X chromosomes makes a girl and an X and a Y chromosome makes a boy.

Question 9

What is sexual reproduction?

Answer 9

Sexual reproduction requires two parents. The offspring is not a clone since it is made from two sets of genes. This causes variation

Question 10

What is the genotype?

Answer 10

Genotype is the genetic make up of an organism

Question 11

What is the phenotype?

Answer 11

Phenotype is the physical characteristics of an organism e.g. hair colour, eye colour and skin colour

Question 11

How can someone be heterozygous?

Answer 11

If someone has two different alleles

Question 11

What do mutations affect?

Answer 11

Mutation affects an organisms genotype and rarely affects phenotype

Question 12

How can a mutation affect phenotype?

Answer 12

If a mutation occurs within a gene dna bases may be changed or deleted. This changes the reading of the triplets so coding for different amino acids which code for different proteins and so affecting the phenotype

Question 13

What is a haploid cell?

Answer 13

Cells that have 23 chromosomes (or D). They are produced in meosis.

Question 15

What causes variation?

Answer 15

A group of genes controlling a certain variation

Question 17

What are some examples of dominant characteristics?

Answer 17

Dark wavy hair, brown eyes, free ear lobes, freckles and a straight nose

Question 18

What is a dominant allele?

Answer 18

A dominant allele is an allele that expresses itself even if you get it from one or both parents

Question 20

What are examples of plants that can reproduce asexually?

Answer 20

Potato plants, spider plants and daffodils

Question 22

How can you predict the outcome of a genetic cross?

Answer 22

By stating the phenotype ant genotype if the parents and making a punnet square diagram

Question 24

Why is there a roughly the same amount of boys and girls in a population?

Answer 24

Because there is a 50% chance of conceiving a boy and a 50% chance of conceiving a girl

Question 25

What are examples of recessive characteristics?

Answer 25

Straight blonde hair, blue eyes, no freckles, joined ear lobes and upturned nose

Question 26

What is a genetic variant?

Answer 26

A genetic variant is a different version of an allele, which is caused by a change in the DNA. All variants occur from mutation

Question 27

What is environmental variation?

Answer 27

Variation caused by the environment you live in

Question 29

Are most mutations harmful?

Answer 29

Most mutations are harmful; They can cause cancer (cells divide uncontrollably) They can cause the production of abnormal protein channels (channels that allow molecules to be transported through the cell membrane) that do not function properly e.g cystic fibrosis

Question 31

What is a genome?

Answer 31

A genome is the entire genetic material of an organism. All individuals produced by sexual reproduction have different genomes except for identical twins

Question 32

What are the advantages and disadvantages of sexual reproduction?

Answer 32

Advantage: variation in offspring will happen and will adapt to environmental pressure. This will kill out the species with unfavourable characteristics and so the organisms with favourable characteristics will reproduce and the species will continue Disadvantage: it takes to parents. Reproduction is slower so less offspring are produced

Question 33

What is genetic variation?

Answer 33

Genetic variation is the genetic material you inherit from your parents

Question 34

How can someone be homozygous?

Answer 34

If you have two copies of the same allele

Question 35

What is variation?

Answer 35

Variation is the differences within a species

Question 36

What is an allele?

Answer 36

Different forms of a gene

Question 37

How does genetic variation occur?

Answer 37

You have two copies of a gene for each characteristic -one from each parent. So you are different to both your parents

Question 39

What is a mutation?

Answer 39

A mutation occurs when a sequence of DNA bases is altered. They can occur spontaneously

Question 45

What is a diploid cell?

Answer 45

A diploid cell has 46 chromosomes (or 2D). They are produced by mitosis

Question 48

What is meiosis?

Answer 48

Meiosis is the process whereby one parent haploid cell creates 4 daughter cells. It happens in the ovum and the testes

Question 49

What is the first stage of meiosis?

Answer 49

1. The chromosomes are copied 2. These chromosomes line up along the equator of the cell (one from each parent) 3. One member of each pair is pulled to opposite ends of the cell 4. The cell divided in two 5. Two separate cells are formed

Question 50

How do most phenotypes arise?

Answer 50

When a group of genes code for a specific characteristic e.g eye colour

Question 51

How do mutations affect non coding dna?

Answer 51

Non coding dna such as mRNA affect how a gene is expressed. Therefore mRNA may not be able to be replicated and is not produced at all.