Science Test Bi, Genetics & Evolution Wk. 43 2017 (9e)

Question 1

alleles

Answer 1

Different version of gene, one allele is for example B (brown eyes).

Question 2

dominant

Answer 2

When a gene is dominant, it only requires one in the gene pair to make sure the phenotype becomes that trait.

Question 3

recessive

Answer 3

When a gene is recessive, it needs both alleles to be the same recessive for the phenotype to be the recessive gene.

Question 4

heterozygous

Answer 4

One dominant, one recessive (alleles combination, eg: Bb)

Question 5

homozygous

Answer 5

Used as either:
Homozygous Dominant
- The alleles pair are both dominant genes eg: BB
Homozygous Recessive
- The alleles pair are both recessive, eg: bb

Question 6

phenotype

Answer 6

The physical characteristics of the gene, for example if you have the genes (BB), your eyes will be brown, which is your phenotype.

Question 7

genotype

Answer 7

The genes you have, this is either Heterozygous, Homozygous Dominant or Homozygous Recessive.

Question 8

nucleus

Answer 8

The core of the cell. The nucleus contains chromosones which contain the DNA.

Question 9

chromosone

Answer 9

Squashed up DNA in an X-like shape that exists in the nucleus. We have 23 pairs of each chromosone. 2 copies of each except the sex chromosones.

Question 10

DNA

Answer 10

The genetic code that decides what proteins to be made.

Question 11

gene

Answer 11

Basic physical unit of heredity. A gene is a trait that decides how you will be. You have two pairs of each gene, one from each parent. Section of DNA that decides one trait.

Question 12

base pairs

Answer 12

The strands of DNA are held together by base pairs, which are nitrogenous bases, represented by the letters A for adenine, T for thymine, C for cytosine, G for guanine. These hold together the strands by weak bonds, and are the basic code that make up DNA. A only pairs with T, G always pair with C.

Question 13

protein

Answer 13

Long chain of amino acids. They are often enzymes, which create chemical reactions in the body. DNA decides how the protein should be made, and what proteins to be made. They are the building blocks of tissues.

Question 14

Amino acid

Answer 14

Building blocks of protein.

Question 15

Trait

Answer 15

Feature of an organism

Question 16

Diploid cell

Answer 16

The cell has pairs of chromosomes. Most cells are diploid.

Question 17

Haploid cell

Answer 17

The cell has only one of each chromosome. Therefore they have half the amount of chromosomes.

Question 18

Gametes

Answer 18

The male orr female reproductive cell that contains half the genetic material of the organism. When two human gametes meet - that is a sperm cell and an egg cell, you get a zygote, a fertilized egg.

Question 19

Mutation

Answer 19

A mutation occurs when a DNA gene is damaged or changed in such a way that the genetic material is altered, which results in changes in either phenotype or just genotype. This can often result in cancer.

Question 20

Heridity

Answer 20

The passing on traits genetically to offspring fromone generation to another.

Question 21

Genetics

Answer 21

The study of genes, genetic variety and heredity in living organisms.

Question 22

Evolution

Answer 22

The gradual change in features of a species over time.

Question 23

Natural selection

Answer 23

When better adapted organisms survive better and therefore they survive and are able to pass on traits to their offspring, which causes evolution.

Question 24

How are inherited characteristics passed on through generations?

Answer 24

This happens firstly through a process called Meiosis. This is when a Diploid cell first doubles its chromosomes, and splits into two. Then the created cells also split into two, but without doubling the amount of chromosomes, resulting in four haploid cells, which are sperms. These sperms then meet with egg cells of a female, which are also haploid cells, and at random, one egg is fertilized by a sperm, and since each sperm only has half of the chromosomes. This results in an offspring with one half of the fathers genetic material and one half of the mothers genetic material. So the genotype is a mix, and then whatever allele is dominant, or if both are recessive decides the phenotype for each gene.

Question 25

What does DNA code for?

Answer 25

DNA codes for the creation of proteins. In smaller chunks, each section of 3 base pairs codes for one amino acid, which are the building blocks of proteins.

Question 26

What are the 4 base pairs of DNA?

Answer 26

Adenine: A
Thymine: T
Cytosine: C
Guanine: G

Question 27

What is meiosis and what is mitosis?

Answer 27

Mitosis:
Starts with a diploid cell.
The cell doubles its chromosomes.
The cell splits into two, identical diploid cells, which are the same as the parent cell.

Mitosis:
Starts with diploid cell.
The cell doubles it chromosomes
The cell splits into two identical diploid cells.
The two diploid cells split into two without doubling their chromosomes, resulting in 4 haploid cells, each with half of the genetic material, or half of the alleles.

Question 28

What is the basic concept for Mendelian genetics?

Answer 28

The concept of calculating the probability for an organism to have a certain phenotype based on the parents. This is done by a concept called dominant and recessive genes. A gene can either be dominant or recessive. Dominant genes are represented by capital letters, and recessive genes are represented by lowercase letters. If you have one or more dominant genes, that becomes the phenotype, so for a recessive gene to be the phenotype, both alleles must be that recessive gene. This can be calculated with a punnet square, shown below.

      Father
      B    b
M    \_\_\_\_ \_\_\_\_
o  b |Bb |bb  |
t    |\_\_\_|\_\_\_\_|
h  b |bb |bb  |
e    |\_\_\_|\_\_\_\_|
r

Question 29

How do you determine sex?

Answer 29

Humans have 23 chromosones pairs, but not all of these are identical. The last pair of chromosomes are the sex chromosones. These are either X or Y. A combination of XX results in a girl, and a combination of XY results in a boy.

Question 30

What are some examples of genetic diseases?

Answer 30

1. Cystic fibrosis
   - 1 in every 2000
   - Produce thick slem that blocks airways and tubes that carry digestive fluids to the gut.
   - Makes breathing hard, limits absorption of nutrients.
   - Recessive
2. Huntington’s disease
   - 1 in every 20 000
   - Patients do not show signs until 30-s or forties.
   - Brain cells degenerate, patient becomes clumsy & jerky and eventually disabled.
   - Dominant allele
   - Most people have children before they are aware they have the disorder, passing on the gene.
3. Sickle cell anaemia
   - Red blood cells S shape
   - Hard to carry oxygen
   - Recessive
   - Makes you resistant to malaria
   - Causes fatigue and pain

Question 31

Zygote

Answer 31

Fertilized egg

Question 32

Gametes

Answer 32

Sex cell

Question 33

What is selective breeding?

Answer 33

Only allowing organisms with desirable genes and traits to reproduce to create offspring with those traits. Kinda like artificial selection.

Example: Fishing regulations say that you can only keep the biggest fish, which is hurting the fish population so some people selectively breed smaller fish which reproduces and produces more.

Question 34

What is a transgenic organism?

Answer 34

A transgenic organism contains a gene or multiple genes that have been artificially inserted by man. For example there is something known as golden rice, which is rice that has the color yellow, and contains Vitamin A. This could help people in places like Africa where Vitamin A deficiency is very common.

Question 35

How can bacteria become resistant to antibiotics?

Answer 35

We kill all the bacteria that is not resistant, so only the few bacteria that has the mutation which allows them to be resistant to antibiotics survive, which allows them to reproduce, and consequently there are more bacteria that are resistant.

Question 36

Give one example of natural selection.

Answer 36

Peppered moth.
First before industrial revolution there were birches, so white peppered moths survived due to camoflauge, but black ones did not because birds could see them. However during the industrial revolutions there were a lot of black (coal mines etc) so black survived better than white, and after that regulations were created to slow the cutting down of wood, so there were more birch so white survived again.

Question 37

What is embryo screening? Pros & Cons.

Answer 37

Embryo screening is when you take scan a few vitro-fertilized embryos (usually when they are only 8 cells) and you check it for genetic diseases and then you inject the healthy embryos into the uterus.
Pros:
- Get baby that is not sick
Cons:
- Conservative people.
- (they think it is unethical and unnatural and you shouldn’t mess with nature bla bla)

Question 38

Determine heredity of genetic diseases and the symptons of the diseases?

Answer 38

?????

Question 39

What are the pros and cons of selective breeding and genetic engineering.

Answer 39

Selective breeding:

• Pros:
• Natural
• Cheep/Free
• Easy
• Higher profits / Desirable traits
• Cons:
• Risk of disease
• Loss of variety
• No control over genetic mutations
• Can cause discomfort to animals
• Can cause genetic depression

Genetic engineering:

• Pros:
• Can defeat diseases
• Produce desirable traits
• Produce organisms with traits not avaliable with genetic engineering.
• Cons:
• Moral? (Blah)
• Can lead to genetic defects