4.2 biology

angiosperm

large group of plants that produce flowers, seeds, and fruits

receptacle

thickened part of the stem where flower organs grow

calyx

collective name of sepals

sepals

green parts that surround and protect the flower bud and extend from the base of a flower after it has opened

corolla

collective name for petals

petals

modified leaves that surround the reproductive parts of the flowers. Often coloured or unusually shaped to attract pollinators

stamen

male reproductive organ in angiosperms

filament

stamen structure that supports the anther

anther

stamen structure that produces pollen

pollen

male gamete in angiosperm

carpel

female reproductive organ in angiosperms

ovary

part of structure which holds ovules and is located above or below or at the point of connection with the base of the petals and sepals

style

long, slender stalk that connects the stigma and ovary

stigma

receives pollen at pollination and the place where pollen grain germinates, often sticky

nectary

an organ or part of a plant that secretes nectar and attractive scent

where does development of the male gamete occur

the pollen sacs of the anther

what is the tapetum

a layer of cells around the pollen sac that provides nutrients

what are the cells in the pollen sac called

diploid micropore mother cell

what happens to the microspore mother cell

divided by meiosis to form a tetrad of 4 haploid cells

what happens to the tetrad of haploid cells

divide by mitosis to form a pollen grain with 2 haploid nuclei

what are the 2 haploid nuclei called

tube nucleus and generative nucleus

what happens to the generative nucleus

divides by mitosis to form 2 male gamete nuclei

what happens when the pollen is mature

the outer layers of the anthers dry out causing tension in the lateral grooves which pulls the walls of the anther apart and the edges of the pollen sacs curl away

how does pollen grains leave the sac

an opening called the stomium exposed them and the wind/insects carry them away

where does the development of the female gamete take place

the ovary

pollination

transfer of pollen from anthers to mature stigmas of a plant of the same species

cross pollination

the transfer of pollen between two plants of different genetic make-up (eg. another plant of the same species)

self-pollination

the transfer of pollen between flowers of identical genetic constitution

dioecious plants

individual plants that are strictly either male or female

monoecious plants

bear both male and female reproductive structures

dichogamy

where stamens and stigma ripen at different times

protandry

the stamens (male parts) ripen and release pollen before the stigmas (female parts) become receptive

protogyny

the stigma (female parts) ripens and become receptive before the anthers release pollen