Flowers and fruits

Question 1

what is the function of flowers?

Answer 1

for pollination and fertilization

Question 2

what are the 4 concentric rings in an ideal flower, what are they for? what are their parts?

Answer 2

1. Sepals → outer ring
   Enclose and protect the flower bud before it blooms
2. Petals →
   Typically bright and fragrant to attract pollinators
3. Stamens → male parts
   Filament → the stalk
   Anther → produces pollen
4. Carpels (pistils) → female parts, center of flower
   Can be one or more
   Stigma → catches pollen
   Style → the stalk; connects stigma to ovary
   Ovary → contains 1 or more ovules. Ovules turn into seeds, while the ovary will turn into the fruit

Question 3

what is pollination?

Answer 3

is the transfer of pollen grains from the anther of one flower (where it was formed) to the stigma of another flower. Does not guarantee fertilization.

Question 4

what is pollination syndrome?

Answer 4

is the set of floral characteristics exhibited by a plant and is associated with a specific type of pollinator

Question 5

what are floral characteristics?

Answer 5

Flower shape
Flower size
Colour
Odour
Timing of flowering
Nectar
Pollen production

Question 6

what are the two types of pollinators? examples

Answer 6

Abiotic:
Wind
Water
Biotic:
Bats
Bess
Beetles
Birds
Butterflies
Flies
moths

Question 7

how do plants attract animal pollinators?

Answer 7

use visual cues (colours/patterns) and odours to attract, and reward such as food (nectar and pollen)

Question 8

what do plants with abiotic pollinators typically look like?

Answer 8

typically have small colourless flowers with no scent that produce a lot of pollen

Question 9

what are angiosperms? what is there main characteristic?

Answer 9

(flowering plants) → produce seeds that develop inside of ovaries that mature into fruit

Question 10

what are sporophytes? how are they identifiable?

Answer 10

• adult diploid generation → dominant generation
• Recognizable with roots, stems, leaves, cones/flowers
• Provides nutrition to the non-photosynthetic gametophyte

Question 11

what is the simplified life cycle of an angiosperm?

Answer 11

Sporophyte → spores → gametophytes → gametes → fuse to form diploid cell

Question 12

gametophyte adults in angiosperms are:

Answer 12

-microscopic and do not exist as independent photosynthetic plants

Question 13

where is a male gametophyte plant found, what is it made of?

Answer 13

is found in the pollen grain
made of 2 parts:
1. a tube cell
2. generative cell

Question 14

why are sperm dependent on pollen tube formation?

Answer 14

Sperm of seed plants are not flagellated and therefore depend on the processes of pollination and pollen tube formation for transport to the ovary

Question 15

in what state do pollen grains arrive at the stigma? what are the steps involved in pollen tube formation?

Answer 15

• pollen grains arrive at stigma in dehydrated condition and need to take up large amounts of fluid to germinate and form a pollen tube
  1. Pollen arrives at stigma
  2. Pollen grain take up large amount of fluid;this fluid stimulates the germination of pollen tube
  3. Growth of pollen tube involves a pattern of cytoplasmic streaming and allows for rapid construction of new plasma membranes and cell walls
  4. As the tube grows, sperm that are produced by the generative cell are carried to the egg for fertilization

Question 16

what happens to the generative cell? why is it called double fertilization? what happens to the sperm?

Answer 16

• A generative cells produces 2 sperm cells through single mitotic division
• 1 cell fertilizes the egg
• 1 cell joins the 2 polar nuclei of the female gametophyte to produce endosperm (tissue), which is a source of nutrition for the sporophyte embryo during growth (seed germination)

Question 17

what did pollen/pollination/pollen tube formation allow?

Answer 17

• allowed for movement of life onto land.

- Allows fertilization to occur over great distances without the need for environmental water for sperm to move through

Question 18

what happens to an ovule? what if there are more than one ovules?

Answer 18

• gets fertilized by sperms and produces a seed

- then each one will be fertilized by a different sperm, each from a distinct pollen grain, and will produce a seed

Question 19

what are the 3 components of a seed? what do they do?

Answer 19

1. Seed coat → hard outer covering which protects from disease and desiccation
2. Embryo → the fusion of the sperm and egg; divides by mitosis to eventually form sporophyte plant
3. Food source → endosperm; embryo uses this to form meristems until they are big enough to break through the seed coat and begin taking up water and nutrients from the environment

Question 20

what happens to the ovary as seeds are developing?

Answer 20

the ovary walls thicken into a fruit

Question 21

what is a pericarp? what are its parts, what are their features?

Answer 21

• Mature ovary
  1. Exocarp → outermost layer “skin”
• Can be soft, fuzzy, thin, leathery, thick, hard, peelable
  2. Mesocarp → middle layer
• fleshy, usually the layer that is eaten
  3. Endo carp → innermost layer that directly surrounds seed
• Can be hard/stoney, papery/thin, or soft/fleshy

Question 22

what is the function of a fruit?

Answer 22

to protect the dormant seeds inside, and aid in dispersal by either wind or animals

Question 23

what is the function of a seed?

Answer 23

dispersal and dormancy and nourishment of embryo

Question 24

what are 4 types of dispersal? how do they do this, and what are an example?

Answer 24

1. parachuting/propelling → fruits that have dry outer coverings which catch the wind and carry them away
   Eg. wings of a maple fruit
   Eg dandelion seeds
2. barbs/hooks → dry fruits may have barbs/hooks to enable them to cling onto animals fur and be carried away to new locations
   eg. longspine sandbur
3. Explosive dispersal → seed pods of some dry fruits burst open and project seeds away from parent plant
   eg. pea pods
4. Ingestion → fleshy fruits are sweet/nutrient dense/brightly coloured so that animals eat them. They go through the digestive tract and are excreted in feces in a different location
   eg. cherries

Question 25

where are female gametophytes found in angiosperms?

Answer 25

in the ovule

Question 26

how is an egg produced?

Answer 26

Diploid cells within an ovule divide by meiosis to form haploid megaspores which then divide by mitosis to form a female gametophyte which produces an egg

Question 27

how is a sperm produced?

Answer 27

Diploid cells within the anther divide by meiosis to form haploid microspores which then divide by mitosis to form the male gametophyte → pollen grain, which produces sperm

Question 28

how do you calculate percent germination?

Answer 28

Number of germinated pollen grains/ total number of pollen grains X 100%
Eg. 9 grains had tails/21 pollen grains X 100% = 42.9% viable pollen grains

Question 29

what are tepals?

Answer 29

petals and sepals that are formed together, and look the same