Genetics and Evolution (Term 2 2022)

Question 1

Genes (four points)

Answer 1

• Segments of DNA
• carry instructions for traits of an organism
• Contained on chromosomes in the nucleus of the cell
• basic units of heredity

Question 2

DNA (four points)

Answer 2

• deoxyribonucleic acid
• double helix shape
• contains genetic information responsible for development and function
• contained in genes (and chromosomes)

Question 3

DNA’s double helix looks like a twisted ladder, where the steps are the bases:

What do the bases decide?

Answer 3

• adenine, thymine, guanine, cytosine

- the order of the bases decides your species, hair colour, eye colour, etc.

Question 4

DNA’s double helix looks like a twisted ladder, where the sides are:

Answer 4

alternating sugar and phosphate molecules.

Question 5

Genome

Answer 5

The complete set of DNA/genetic information in an organism.

Question 6

Chromosomes

Answer 6

• are made up of genes

- humans have 46 (23 pairs)

Question 7

Human sex cells (four points)

Answer 7

• the 23rd pair of chromosomes
• referred to as haploid gametes
• sperm (males), egg (females)
• contain 23 unpairs chromosomes, when sexual reproduction occurs (fusion of gametes) the total number of chromosomes is preserved (they add up to 46 chromosomes)

Question 8

Chromatins

Answer 8

complex of DNA and proteins that form chromosomes

Question 9

Chromatid

Answer 9

one half of a replicated chromosome

Question 10

Helical Strand

Answer 10

one strand of the double helix of DNA (which has two strands)

Question 11

Nucleotide

Answer 11

basic building block of nucleic acids (RNA and DNA)

Question 12

RNA (three points)

Answer 12

• ribonucleic acid
• present in all living cells
• single stranded but similar to DNA

Question 13

Base Pairs

Answer 13

Bases on opposite strands pair together (Adenine and Thymine, Cytosine and Guanine)

Question 14

Telomere

Answer 14

Protective “caps” on the end of DNA molecules, that prevent chromosomes from fraying or sticking together.

Question 15

Centromere
Q arm
P arm

Answer 15

Centromere:constricted region of a chromosome that separates it into a long arm and a short arm

Q: long arm

P: short arm

Question 16

Mitosis

Answer 16

cell division that allows a cell to grow and replace old/sick cells

Question 17

Meiosis

Answer 17

Sexual reproduction (fusion of gametes)

Question 18

Alleles

Answer 18

Versions of a trait

Question 19

Homozygous

Answer 19

When both alleles in a genotype are the same

Question 20

Heterozygous

Answer 20

When the alleles in a genotype are different

Question 21

Genotype

Answer 21

The unique combination of alleles for an inherited gene, can be dominant or recessive

Question 22

Phenotype

Answer 22

Physical trait that is inherited

Question 23

Co-dominance in traits

Answer 23

when both traits are expressed, e.g. red and white traits will create red and white stripes/spots/etc.

Question 24

Incomplete Dominance in traits

Answer 24

When traits are blended together, e.g. red and white makes pink

Question 25

Sex-linkage in traits

Answer 25

When traits are only expressed in the male or female parent

Question 26

genetic variation

Answer 26

When a child will be similar but not identical to their parents

Question 27

environmental variation

Answer 27

when the characteristics of a species change due to environmental conditions (e.g: tanned skin, height of a plant in shade, etc.)

Question 28

Autosomal Inheritance

Answer 28

When a characteristic is carried by a normal cell

Question 29

Sex-linked Inheritance

Answer 29

When a characteristic is carried by a sex cell