Topic 6 (Inheritance, Variation And Evolution)

Question 1

What are chromosomes

Answer 1

Chromosomes are long molecules made up of DNA

Question 2

What is DNA

Answer 2

DNA stands for deoxyribonucleic acid, it is a chemical that all genetic material in a cell is made of

Question 3

What is a gene

Answer 3

A gene is a small section of DNA found on a chromosome

Question 4

What do genes do

Answer 4

Each gene codes for a particular sequence of amino acids which are put together to make a specific protein

Question 5

What is a genome

Answer 5

A genome is a fern for the entire set of genetic material in an organism

Question 6

DNA is made up of repeating units called nucleotides. What is a nucleotide

Answer 6

A nucleotide consists of a sugar, aphosphate group and one base. One of four different bases joins to the sugar and the sugar joins to the phosphate.

Question 7

What are the bases that join to nucleotides

Answer 7

A,T,C and G
A always pairs up with T
C always pairs up with G

Question 8

What are ribosomes and what do they do

Answer 8

Ribosomes are tiny structures that make proteins, they make proteins using the code in the DNA.

Question 9

How do the ribosomes get the code to make proteins

Answer 9

•DNA can not get out of the nucleus but the ribosomes are in the cell membrane
•The cell needs to get the code from the DNA to the ribosome
•This is done using mRNA which is made by copying the code from the DNA and acts as a messenger from DNA to ribosome

Question 10

What are mutations

Answer 10

Mutations are changes to the genetic code.

Question 11

What is the problem with mutations

Answer 11

Mutations can have very little or no effect however some mutations can have a serious effect on a protein. Sometimes the mutation may code for an altered protein with a change in its shape, this could effect its ability to function and cause serious problems for the person

Question 12

There are three types of mutation, what are they

Answer 12

•Insertion-Adding a random base to the code
•Deletion-Removing a random base from the code
•Substitution-When a base is replaced by another base

Question 13

How does sexual reproduction work

Answer 13

•The mother and father produce gametes by meiosis
•Each gamete contains 23 chromosomes, half the amount of a normal human body cell
•The gametes fuse together to form a full cell with the full 46 chromosomes
•This is why the offspring inherits characteristics from both parents

Question 14

What is sexual reproduction

Answer 14

The fusion of male and female gametes, to create offspring with a mixture of their parents genetic information

Question 15

What is asexual reproduction

Answer 15

Asexual reproduction happens by mitosis, an ordinary cell makes a new cell by dividing into two

Question 16

What is meiosis

Answer 16

Meiosis
•Before cell starts to divide, it duplicates its genetic information, forming two armed chromosomes
•In the first division in meiosis the chromosome pairs line up down the middle, they are then pulled apart so each new cell has one copy of each chromosome
•In the second division, the chromosomes line up down the middle again, they are pulled apart leaving each of the four gametes with only a single set of chromosomes in it
•Each gamete is genetically different as the chromosomes are shuffled up during meiosis

Question 17

What are the advantages of sexual reproduction

Answer 17

•Variation in offspring
•Survival advantage
•Natural Selection

Question 18

What are the advantages of asexual reproduction

Answer 18

•Only one parent needed
•Less energy required
•Faster
•Identical offspring in favourable conditions

Question 19

What is the 23rd pair of chromosomes known as

Answer 19

XX or XY, these chromosomes decide your sex

Question 20

If you have XX chromosomes what is your sex

Answer 20

Female

Question 21

If you have XY chromosomes what sex are you

Answer 21

Male

Question 22

What is Hetrozygous

Answer 22

One dominant allele one recessive allele

Question 23

What is homozygous dominant

Answer 23

Two dominant alleles

Question 24

What is homozygous recessive

Answer 24

Two recessive alleles

Question 25

What is a genotype

Answer 25

The combination of alleles you have

Question 26

What is a phenotype

Answer 26

Your physical appearance/characteristics

Question 27

What is cystic fibrosis

Answer 27

Genetic disorder of cell membranes, causes body to produce a lot of thick sticky mucus in the air passages and in the pancreas. It is caused by a recessive allele

Question 28

What is Polydactyly

Answer 28

Polydactyly is a genetic disorder where a baby is born with extra fingers or toes, it is caused by a dominant allele

Question 29

What is embryonic screening

Answer 29

During IVF embryonic screening is analysing an embryos genotype to detect genetic disorders. These alleles can then be removed before embryo is inserted. This in theory means other genes can be removed and sex could be chosen.

Question 30

What are arguments for genetic screening

Answer 30

•Stops people suffering
•Treating disorders cost government a lot of money
•Laws to stop it from going too far

Question 31

What are arguments against genetic screening

Answer 31

•Implies people with genetic disorders are undesirable
•May lead to a time where everyone is made to be the most desirable baby possible
•Expensive