Unit 4 Part 4 - Plants Flashcards
Where are gametes of flowering plants produced?
Females - structures called ovules
Males - structures called pollen grains
What does meiosis do in plants?
Gives rise to the ovules and pollen grains
What does mitosis do in plants?
produce the actual gametes
Why is reduction division not required to produce haploid gametes?
B/c reproductive structures are already haploid
Hermaphroditic?
Flowers with male and female structures
Self pollination?
A form of sexual reproduction b/c gametes are produced by meiosis and there is a fusion of gamete nuclei to form an embryo
Disadvantage if self reproduction?
Loss of genetic variation
Cross pollination?
Transfer of pollen produced on one plant w/ another plant
How do flowers with petals attract pollinators?
They use shapes, markings, and clours
Where does pollen develop?
Develops w/in structures called anthers
Stigma?
A sticky structure that’s held upright and pollen grains can easily adhere to when pollinators move onto a dif flower
Pollen tube?
Pollen that adheres to a stigma
Fertilization in plants?
Pollen tube: carries 2 male nuclei
Ovule: 3 haploid nuclei
One pollen nuclues fertilizes one ovule nuclues to create zygote, other pollen nuclues fertilizes other two nuclei to create endosperm
Endosperm chromosome
Has 3 b/c three nuclei were used in order to make it
Growth of endosperm
Growth of this triploid tissue produces nutritive endosperm w/in seed that will nourish early plant embryo
Common insect pollinators?
Bees, wasps, flies, butterflies, and moths
Where are stamens of insect pollinating flowers located?
Usually deep inside the flower so that insects drinking nectar will brush up against the pollen grains
Flower parts?
- Sepal
- Petal
- Anther
- Pollen
- Filament
- Stigma
- Style
- Ovary
- Ovary
Sepal function?
Protecting developing flower while its inside the bud
Petal function?
Usually colourful to attract pollinators
Another function?
The part of stamen ( male portion of flower) that produces male sec cells (pollen)
Pollen function?
Contains male nuclei used for fertilization
Filament function?
The stalk of the stamen that holds up the anther
Stigma function?
Sticky part of a carpel ( female portion of flower) which pollen lands on
Style function?
Part of the carpel that supports stigma
Ovary function?
Base of carpel, containing one or more ovules
Ovule function?
Chamber w/in an ovary where the female nuclei develop
Mechanisms evolved to promote cross - pollination?
- Different maturation times for pollen and ovules
- Chemical self-incompatibility mechanisms are used
- Some flowering plants produce flowers with only either male or female parts
- Some species can only produce their own gender ( must have one sex features)
- Wind
Self incompatibility mechanism?
When pollen of a plant lands on stigma of flower of same plant, protein interactions occur that reduce or stop growth of pollen tube
Specifics of self - incompatibility mechanism?
- Pollen grain on stigma fails to germinate into a pollen tube
- Pollen grain germinates but doesn’t enter through stigma into style
- Pollen tube enters ovule but pollen nuclei degenerate before fertilisation can occur
- Fertilization occurs but plant embryo degenerates during early growth
Conditions needed for a seed to germinate?
Water
- To re hydrate the dried seed tissue
Oxygen
- To allow aerobic respiration to release adenosine triphosphate
Appropriate temp
Radical?
The initial root structure that emerges first
What structure appears first in a plant?
The hypocytal
