Section 7 - Reproduction and Inheritance

Question 1

What does the nucleus in your cells contain?

Answer 1

contains your genetic material in the form of chromosomes

Question 2

What is a chromosome?

Answer 2

Long lengths of DNA coiled up

Question 3

What is a gene?

Answer 3

• A gene is a short section of DNA
• Different version of the same gene is called alleles

Question 4

What are diploid cells?

Answer 4

They have two copies of each chromosome, arranged in pairs
- Humans have 46 chromoseomes in total
- Diploid number of human = 46

Question 5

Genome def

Answer 5

all the DNA that makes up an organism

Question 6

What do gene’s do?

Answer 6

Chemical instruction that codes for a particular protein

Question 7

How can organisms reproduce?

Answer 7

• asexually, mitosis
• sexually, meiosis

Question 8

How does mitosis work?

Answer 8

Ordinary cells make new ones by dividing in two.
This is how plants and animals repair and grow.

Question 9

What is asexual reproduction

Answer 9

• organisms that produce offspring through mitosis
• offspring contains identical genes to the parent = no variation

Question 10

steps of mitosis

Answer 10

1. DNA spread out in long strings
2. Cells gets signals to divide so cell forms X shaped chromosomes. One half one cell and the other the duplicate
3. Line up at the centre and fibres pull apart. Each half to one end
4. membranes around chromososmes become the nucleus.
5. Lastly cytoplsm divides

Question 11

How does meiosis work?

Answer 11

• Zygote goes through cell division + becomes an embryo
• Inherits features from both parents = genetic variation

Question 12

Chromosomes in sexual reproduction

Answer 12

each gamete contains 23 chromosomes

Question 13

Steps of meiosis 1st division

Answer 13

1. DNA starts to duplicate
2. Chromosomes line up in pairs at the centre of the cell. Mix between mother and father genes
3. Pairs pulled apart by cell fibres

Question 14

Steps of meiosis 2nd division

Answer 14

1. chromososmes line up again in the center of the cell and fibres pull them apart
2. 4 haploid gametes formed each gamete contains a single set of chromosomes

Question 15

Adaptations of plants for sexual reproduction

Answer 15

• Insect pollination: Brightly coloured petals + scented flowers + make big sticky pollen grains
• Wind pollination: Small dull petals + no scent + light pollen grains. Also long filaments and feathery stigma

Question 16

Fertilisation def

Answer 16

fusion of opposite sex gametes