D3.2 Inheritence

Question 1

What is a gamete?

Answer 1

Specialised reproductive cells that cure during fertilisation.
Produced by meiosis of gonands (cells within specialised organs that produce gametes)

Question 2

What is a haploid cell?

Answer 2

Contains a single set of chromosomes (23)— gametes are haploid

Question 3

What is a zygote?

Answer 3

Formed by the musk on of one male parent and one female parent gamete to form a diploid (46 chromosomes) zygote.

This means diploid cells have 2 copies of each autosomal gene.

Question 4

What does hermaphroditic mean?

Answer 4

Organism with both male and female reproductive organs, e.g., pea plant

Question 5

Describe the male plant reproductive organs and their function

Answer 5

Stamen:

Compromised of the elongated anther—>contains the male gametes=pollen, which is held up by a thin filament

Question 6

Describe the female plant reproductive organs and their function

Answer 6

Pistil:

Has a swollen base called an ovary that surround female gametes=ovules

A style extends from the ovary and terminates in a structure called the stigma

Question 7

How does fertilisation occur in plants?

Answer 7

Pollen arrives at the stigma

There it grows a pollen tube which carries the pollen (containing the haploid nucleus) down to the hollow style to an ovule of the ovary

Question 8

What is the difference between self-pollination and cross-pollination?

Answer 8

Self pollination— pollen of the same plant lands on the same stigma

Cross-pollination— pollen from a different plant lands on another stigma

[HOWEVER pollen/stigma interaction highly selective—>try and stop self-pollination due to weak genetic variation]

Question 9

What are the P, F1, and F2 generations?

Answer 9

P—Parent generation of a genetic cross
F1—offspring of P
F2—offspring of F1(will possess some characteristics not seen in F1)

Question 10

State an application of performing genetic crosses in plants

Answer 10

Breeding climate-smart crops that can cope with climate change, extreme weather, drought, flooding

Question 11

What are genes?

Answer 11

Segments of DNA that code for a specific protein—

they are in identical positions on each of the homologous chromosomes do an individual will have 2 copies of each gene (one from each parent)

Question 12

What is a homologous chromosome?

Answer 12

A pair of chromosomes of the same type that come from each parent (eukaryotes)

Question 13

What are alleles?

Answer 13

An allele is a variant of a gene

Although genes are on identical positions on each chromosome, they each may differ by a few bases:

These different forms of genes are called alleles

Question 14

What is a genotype?

Answer 14

A combination of alleles that form a specific set of DNA.

Question 15

What is the difference between homozygous and heterozygous?

Answer 15

Homozygous— when a gene has 2 identical alleles

Heterozygous— when a gene has 2 different sets of alleles

Question 16

What is a phenotype?

Answer 16

Physical traits and characteristics that are expressed in an organism or cell

Question 17

Homozygous dominant vs homozygous recessive

Answer 17

Dominant: Both alleles for a trait are dominant: FF
Recessive: ff

Question 18

What is phenotype plasticity?

Answer 18

The ability of an organism to adapt in physical characteristics or traits in response to environmental influences:

Not caused by changes in genotype, the change doesn’t even need to be permanent

Example— seasonal polyphenism of the butterfly

Question 19

What is a recessive genetic condition, give an example?

Answer 19

Individual would need to be homozygous recessive

E.g., PKU (phenylketonuria)

Question 20

What is PKU caused by?

Answer 20

A mutation in a gene on chromosome 12.
This gene codes for an enzyme used in metabolism (PAH) that converts amino acid Phe to Tyr.

Phe is cell not broken down, toxic levels build up—> (symptoms: tremors, seizures) if condition left untreated, brain damage.

Teased early after birth, treatment is a diet low in protein.