Plants Flashcards
flower
contains male and female sexual organs
carpel
produces female gametes + provides structures/conditions necessary for fertilisation
stamen
produces male gametes (pollen) and provides correct structures and conditions necessary for pollen transfer
petals
attract pollinators
anther
produces pollen grains (contain plant’s male gametes)
filament
holds the anther in a position where it is able to transfer its pollen to an insect/mammal/bird
stigma
traps pollen from other flowers
style
supports and presents stigma in position where it can receive pollen (from insect/bird/mammal)
ovary
contains ovules (which contain female gametes) which develop into seeds after fertilisation
ovules
produces and contains female gametes, which upon fertilisation develop into seeds
nectary
produces nectar (sweet liquid that pollinators feed on)
sepals
protects leaves (while in bud)
pollination
transfer of pollen from anther to stigma
when does fertilisation occur
pollen nucleus fuses with nucleus in ovule
brightly coloured flowers are usually pollinated by
insects
description of sepal
green part at the top of the stem, underneath the petals
description of stamen
the male part of the flower consisting of the filament and the anther
description of filament
the stalk that supports the anther
description of anther
coloured, usually with a powdery appearance
description of stigma
usually green and the tallest part of the inside of the flower, and with a sticky, waxy layer
description of style
thin structure that supports the stigma and is above the ovary
description of carpel
female part of the flower that contains the stigma, style and ovary
description of ovary
green, bulb-shaped part near the bottom of the flower
description of ovule
structures within the ovary
two types of pollination
self and cross
what is self pollination
transfer of pollen
grains from the anther of a flower to the stigma
of the same flower or a different flower on the
same plant
advantage of self pollination
do not need to rely solely on pollinators such as insects
disadvantage of self pollination
- reduces genetic variation within a population of plants
- reduces ability to of a population to respond to changes in environment (such as changes in climate or introduced diseases)
what is cross pollination
transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species
advantage of cross pollination
- genetic variation increases within a population of plants
- improves the ability of the population to respond to changes in the environment and to disease
disadvantage of cross pollination
relies on pollinators
petal in wind pollination
small and usually dull in colour because they do not need to attract insects
petal in insect pollination
large and brightly coloured to attract insect pollinators
anther in wind pollination
loosely attached and dangle outside the flower so its pollen can be blown easily by the wind
anther in insect pollination
located inside the flower to brush against insects
stigma in wind pollination
loosely attached and dangle outside the flower so they can catch wind-borne pollen from other plants; often appear feathery
stigma in insect pollination
located inside the flower to brush against insects
conditions for germination
Water, Oxygen, Warmth
How many number of flowers/plants do wind pollinated and insect pollinated have?
wind pollinated: many small
insect pollinated: fewer, larger
What is the plant population growth patter in wind pollinated and insect pollinated flowers?
wind pollinated: dense population
insect pollinated: small groups
How are the petals in wind and insect pollinated flowers?
wind pollinated: dull and small
insect pollinated: bright large
What are two adaptations of an insect pollinated flower that a wind pollinated flower doesn’t have?
good scent and nectar
How are the pollen grains in wind pollinated flowers?
smooth, small, light, not many
How are the pollen grains in insect pollinated flowers?
sticky, large, heavy, spiky, many
How are the stamens in wind pollinated flowers?
pendulous, long filaments, exposed anthers
How are the stamens in insect pollinated flowers?
short filaments with enclosed anthers
How are the carpels/ovary in wind pollinated flowers?
exposed
How are the carpels/ovary in insect pollinated flowers?
enclosed
How is the stigma’s surface in wind pollinated flowers?
sticky, feathery, exposed
How is the stigma’s surface in insect pollinated flowers?
sticky, flat, enclosed
Describe pollination
the transfer of pollen
grains from an anther to a stigma
What are the effects of SELF-POLLINATION on a population in terms of variety, capacity to respond to changes in environment + reliance on pollinators?
- fewer genetic variation
- lower capacity to respond to changes in environment
- relies less on pollinators
What are the effects of CROSS-POLLINATION on a population in terms of variety, capacity to respond to changes in environment + reliance on pollinators?
- more genetic variation
- higher capacity to respond to changes in environment
- relies a lot on pollinators
When does fertilisation occur in plants?
when a pollen nucleus fuses with a nucleus in an ovule
what is germination
development of a plant from a seed
What are three factors needed for germination of seeds?
water, oxygen and warmth
What enzymes are used in germination and how?
amylase breaks down starch into glucose, which is to be used by the embryo to grow
Describe the growth of the pollen tube and its entry into the ovule.
- pollen lands on stigma and are recognised by the receptors on stigma surface
- pollen tube grows down the style towards ovary
- pollen tube penetrates wall of the ovary to reach the ovule
- sperm cell inside the pollen grain moves down pollen tube, reaching the ovule and they fuse to form a zygote (fertilisation)
- the petals, stamen and sepals wither and fall from flower
- ovary grows and matures into fresh fruit: fertilised ovule turns into seed of the fruit
