13.3 Sexual Reproduction in Seed Plants

Question 1

Seeds function

Answer 1

• To protect and nourish the embryo
• To carry the embryo to new locations (dispersal)

Question 2

Germination

Answer 2

when the plant starts to grow from the
seed

Question 3

Seed dispersal

Answer 3

• Dispersal moves the seeds to new locations where there may be less competition from other plants, increasing the chances of survival
• Wind: seeds catch the wind and are blown away (example: dandelions or sycamore “helicopters”)
• Animal food: fruits are tasty to animals, so when they eat them the seeds are not digested and pass through the animal unharmed

Question 4

Monocot vs dicot seed

Answer 4

• Endosperm: part of the seed that is the “stored food” – is the nutritive tissue
• Cotyledon: part of the seed that holds the embryo

Question 5

Sexual reproduction benefits

Answer 5

• Increase in genetic diversity
• Seeds can be dispersed away from parent plant to areas where survival may be greater
• Seeds can remain dormant for long periods of
  time until it is suited for their survival
• GYMNOSPERMS have their seeds transferred by
  wind

Question 6

Sexual reproduction in angiosperms

Answer 6

• Angiosperms are flowering plants that have their seeds encased in a fruit
• Fruit: the mature or ripened ovary of the plant
• Humans and animals can eat these fruit as a viable
  food source!

Question 7

How can we tell if it is a monocot or a dicot from
the flowers?

Answer 7

• Monocot flowers have their petals in multiples of 3
• Dicot flowers have their petals in multiples of 4 or 5

Question 8

Male sex organs

Answer 8

• Stamen: the male reproductive organ
• Composed of the anther and a filament
• Anther: produces pollen

Question 9

Female sex organs

Answer 9

• Carpel: the female reproductive organ
• Composed of the stigma, style, and ovary/ovule
• Stigma: sticky surface on top of the style that acts as the landing site for the pollen grains
• Ovary: contains ovules waiting to be fertilized
• Ovules, when fertilized, form a new seed!

Question 10

Pollination

Answer 10

• Pollen grains are transferred from the anther to the
  stigma (and then the ovule) 🡪 pollination
• This can happen by wind or by animals
  (pollinators)

Question 11

Types of pollination

Answer 11

• Most angiosperms have to cross-pollinate, where
  pollen grains have to be transferred from one plant
  to another
• Some can self-pollinate- this means they can
  transfer pollen to itself (requires both the stamens
  and carpel)
• Ex: Mendel’s Pea Plant

Question 12

Fertilization

Answer 12

• The pollen sent from the anther to the stigma contains
  two haploid sperm nuclei
• Once the pollen reaches the ovary, two things are
  created (called double fertilization):
• one diploid zygote is formed (between one sperm cell
  and the egg cell)
• one triploid cell is formed (between the second sperm
  cell and two polar bodies)to develop into the seeds
  endosperm

Question 13

Fruit

Answer 13

• Fruit is the mature ovary of the flower, which contains the seeds that reproduce
• Once the ovule is fertilized, the ovary wall develops into the pericarp
• Pericarp: the fruit wall (can be fleshy or dry)
  Function:
• To protect the seed
• To aid in the dispersal of the seed