2101 - Flowers & Pollination

Question 1

What is a Flower

Answer 1

A flower is the reproductive organ of an angiosperm plant.

Question 2

Flower Main Functions

Answer 2

Production of Male and Female Gametes (sex cells).

Dispersal of pollen via Insect, Wind or other vectors.

Production of fruits & seed

Question 3

Angiosperm vs Gymnosperm

Answer 3

Flowers are a structure where the seed can develop within an enclosed ovary.

Gymnosperms seed borne naked on Cones.

In angiosperms, fruits may later develop as a food resource to aid seed dispersal.

Question 4

Where do flowers develop

Answer 4

Flowers develop only at the end of a vegetative shoot. Which ceases to grow and puts all its energy into forming flowers, and after pollination, seeds.

The main function of flowers are to enable sexual reproduction and therefore production of seeds and fruits.

Question 5

Dicot flower parts - Male

Answer 5

Stamen, male sexual organ which includes:

Anther - produces pollen

Filament - hold the anther in place, attaches anther to the receptacle.

Question 6

Dicot flower parts - Female

Answer 6

Carpel/Pistil, female sexual organ which includes:

Stigma - a sticky, receptive surface, pollen grains must adhere to the Stigma

Style - holds Stigma in place, joins the Stigma to the Ovary.

Ovary - Contains the Ovules. Where seeds develop, will develop into fruit after pollination occurs.

Ovules - will become a seed

Question 7

Dicot flower parts - Petals

Answer 7

Leaf like structure, brightly coloured. Attracting pollinating insects.
Protect the sexual organs.

Collectively called the Corolla.

(wind pollinating plant have much less showy petals)

Question 8

Dicot flower parts - Pedicel

Answer 8

Flower stalk or stem, sometimes called Rachid

Question 9

Dicot flower parts - Receptacle

Answer 9

On top of the Pedicel, supports the rest of the flower.

Question 10

Dicot flower parts - Sepals

Answer 10

Leaf-like structure to protect the flower when it is in bud, usually green.
Collectively called the Calyx

Outermost whorl. Not present on all flowers.

Question 11

Dicot flower parts - Nectaries

Answer 11

Produce nectar for luring insects deep inside the flower. Located at the base of the petals.

Question 12

Dicot flower parts - Brats

Answer 12

Leaf like structure at the base of a flower. Can sometimes be larger than the flower. (Hydrangea)

Question 13

Monocot flower parts - Tepals

Answer 13

In some plants, especially monocots, the sepals and petals cannot be distinguished easily.

TEPALS

Tulipa spp.

Question 14

Male sexual organ revisited

Answer 14

Stamen (collective)

Anther is where pollen is produced

Filament is the stalk which holds the anther

Question 15

Female sexual organ revisited

Answer 15

Carpel or Pistil (collective)

Stigma is the topmost part, designed to receive pollen, often sticky or ridged.

Style is the stalk that supports the stigma

Ovary is at the base and contains the ovules. Will become the fruit.

Ovules hold the female gamete. Will become the seed.

Question 16

Perfect / Hemaphroditic flowers

Answer 16

Flowers the posses both male and female flower parts. Most plant species belong to this group.

Rosa, Prunus

Question 17

Imperfect 01 - Monoecious

Answer 17

Separate Male and Female flowers on one plant. (can still self pollinate)
The plant is still hermaphroditic.

Fagus sylvatica (Beech)
Juglans regia (walnut)
Betula pendula (Birch)
Cucurbita pepo (courgette/squash)

Question 18

Imperfect 02 - Dioecious

Answer 18

Male and Female flowers growing on separate plants. The plants are heterosexual.

Ilex aquifolium
Skimmia japonica
Aucuba japonica

Question 19

Wind Pollinated Adaption

Answer 19

Flowers are small and inconspicuous
Petals and Sepals greatly reduced
Nectaries often Absent
Large amount of pollen produced
Pollen Grains smooth and light for easy dispersal
Anthers loosely attached - slight movement initiates pollen release
Large feathery Stigmas hang outside the plant on extended Styles

Zea mays (sweetcorn)
Quercus rubor
Fagus sylvatica

Question 20

Insect Pollinated Adaption

Answer 20

Flowers are relatively large
Petals (or bracts) often brightly coloured and UV reactive
Flowers may incorporate nectar guides or landing pads
Often scented (nectaries)
Smaller amounts of pollen produced
Pollen Grains larger, rough or sticky
Anthers and Stigmas may remain inside the flower where pollinaters will brush against them

Rosa rugosa
Digitalis purpurea

Question 21

Environmental Conditions Effecting Pollination - Temperature

Answer 21

Low temperature results in less active pollinating insects, and therefore less insect pollination will occur.

Temperature increase good for pollinators, more active. Rate of pollen production is increased.

Extremely low temperature may result in the death of flowers, particularly if it flowers early in the spring.

Malus (apple), Prunus (Cherry)

Question 22

Environmental Conditions Effecting Pollination - Water

Answer 22

Rain will inhibit insect and wind pollination.
Flying pollinators will be less active in wet weather.
Pollen will become wet and heavy, resulting in less wind borne pollen.
Rain and Hail can also cause damage to flowers, reducing their ability to produce and receive pollen.

Question 23

Environmental Conditions Effecting Pollination - Wind

Answer 23

Will aid in the pollination of Wind-pollinated flowers. Though will reduce the activity of flying insect pollinators. Therefore reducing pollination of insect-pollinated plants.
High Winds can also cause damage to flowers, reducing their ability to produce and receive pollen.

Question 24

Pollination

Answer 24

The transfer of pollen (male gamete) from the Anthers where it is produced to the Stigma which is designed to receive and recognise it.

Question 25

Self-Pollination

Answer 25

Transfer of pollen from the anther to stigma of the same flower, or flower of the same plant.

Question 26

Cross-Polination

Answer 26

The transfer of pollen from the Anther of one flower to the Stigma of another, of the same or related species.

Question 27

Cross-pollination benefits

Answer 27

Genetic diversity, increase the likelihood of species survival. Able to survive more varied environmental conditions.

Question 28

Self Pollination Strategies

Answer 28

Monoecious Plant
Separate male and female flowers, physical distance

Dioecious Plants
Separate male and female plants, so can’t be self-pollinated

Self-incompatibility
unable to self-pollinate

Protandry / Protogyny
Sexual flower parts mature at different times

Special Flower Structure
Adaptions to negate self-pollinaisation, and favours cross pollination.
Primula vulgaris (cowslip)