8.3.1- 8.3.2 Sexual rep + plants

Question 1

Describe the process of combining DNA in sexual reproduction and why it is useful

Answer 1

For any species, variation (to an extent) is useful

Two specimen in a species will have a different pattern of variation

Combining variations from two variants creates more novel variety and speeds up the process of making variants

Question 2

How do organisms solve the issue of having double the amount of DNA via sexual reproduction

Answer 2

they have special lineages of cells in specialised organs with only half the amount of chromosomes/DNA compared to non-reproductive cells

this is achieved via cell division or Meiosis

Question 3

Flowering plants

Answer 3

Angiosperms

Question 4

Unisexual and Bisexual plants

Answer 4

Papaya, watermelon

Hibiscus, mustard

Question 5

Stamen

Answer 5

Male rep part

Produces pollen grains (yellowish)

Question 6

Pistil

Answer 6

Female rep part

3 parts
-Ovary: swollen bottom
-Style: middle elongated part
-Stigma: terminal + sticky

Question 7

Ovary

Answer 7

Contains ovules

Each ovule has an egg cell

Fusion of gametes/ fertilisation and formation of zygote occurs here

Question 8

Pollination

Answer 8

Self: transfer of pollen in the same flower

Cross: transfer of pollen in different flowers

Agents: wind water animals

Question 9

Pollen landing > fertilization

Answer 9

• Pollen from stamen lands on stigma
• Pollen grain grows a pollen tube via which the male gamete reaches the ovary
• In the ovary it fuses with female gametes

Question 10

Changes after fertilisation

Answer 10

• Zygote divides multiple times to form embryo
• Ovule hardens to become a seed
• Ovary ripens into a fruit
• Petals, sepals, stamens etc shrivel and fall

Question 11

Advantages of seed formation for plant

Answer 11

Seed contains embryo capable of growing into a new plants under appropriate conditions (germination), species is preserved

Protection from harsh environmental conditions