Genetics and Sexual and Asexual Reproduction in Plants

Question 1

What are chromosomes and what happens to human chromosomes at fertilisation?

Answer 1

• Chromosomes are thread-like structures made of DNA and protein found in the nucleus of the cell, arranged along the DNA of the chromosome
• Human sperm and egg cells have 23 chromosomes and join at fertilisation to form a zygote with 46 chromosomes

Question 2

What are dominant and recessive genes?

Answer 2

• Dominant genes makes the effect of a recessive gene eg. Brown eyes -B
• Recessive gene is masked by dominant gene and is only expressed if two recessive genes are found together eg. Blue eyes -b

Question 3

What are genetic characteristics?

Answer 3

• Offspring from sexual reproduction are similar to parents but not identical
• Offspring inherits characteristics on the genes that are present in chromosomes found in the gamete eg. Eye colour, hair colour

Question 4

What are genetic and non-inherited factors?

Answer 4

• Genetic factors are controlled by genes but influenced by environment eg. Height is genetic but also our diet eg. Calcium
• AKA acquired factors are not controlled by genes or parents eg. riding a bike

Question 5

What did Gregor Mandel do ?

Answer 5

• Experimented on pea plants and studied the traits eg. The colour
• Noticed that some traits were dominant and others were recessive
• Concluded that all living things pass on their characteristics in predictable ways

Question 6

Functions of male organs

Answer 6

Stamens

1. Sepals: protects flower before blooming
2. Filament
3. Anther (makes pollen)
4. Petals: Attracts insects for pollinatin

Question 7

Function of female organs

Answer 7

Carpels

1. Ovary (products ovules)
2. Style
3. Stigma (where pollen lands)

Question 8

What is pollination?

Explain Animal and Wind pollination

Answer 8

-Pollination: the transfer of pollen from the anther to the stigma
Animal Pollination:
-Brightly coloured petals
-Scented
-Have nectaries, stamens, carpels inside
-Sticky pollen
Wind Pollination:
-No petals usually
-No scent
- No nectaries, stamens or carpels outside
-Light pollen

Question 9

What happens at fertilization in plants?

Answer 9

• After pollen lands on the stigma, it splits open
• A chemical is released to form a hollow pollen tube down through the style to the ovule in the ovary
• Male gametes travel down through the pollen tube + enters into the ovule + joins w/egg

Question 10

Seed and Fruit Formation

Answer 10

1. Ovule develops into a seed
2. Ovary forms fruit around seed
3. Seed coat for a food store
4. Zygote forms the embryo plant inside seed
5. Plumule becomes to shoot// radicle becomes the root
6. Fruit forms around seeds for seed disperse
7. Seed dispersal scatters the seed away from parent plant to avoid competition for light etc

Question 11

What are the 4 Methods of Seed Dispersal

What is the above ground shoot system

Answer 11

Seed Dispersal: 1. Wind eg. Dandelion
2. Water eg. Waterlilies 
3. Animals eg. Blackcurrent 
4. Self eg. Peas 
Above ground shoot system:
1. Stem 
2. Leaves 
3. Flowers 
4. Bud

Question 12

What is asexual reproduction?

Answer 12

No gametes involved and only involves one organism

Eg. Daffodil, strawberry runners

Question 13

What is germination?

Answer 13

The growth of a seed into a new plant