Biology revision

  • Created by: LamisDK
  • Created on: 29-11-17 12:44

Asexual reproduction

A process resulting in the production of genetically identical offspring from one parent

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Sexual reproduction

A process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other

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Sexual reproduction (terms)

Gametes:sex cells.
Zygote:the new cell which is formed by fertilization.
Diploid:a cell which has the full number of chromosomes ,with two complete sets.
Haploid:a cell which only has a single set .
Fertilization:the fusion of male gamete and female gamete to form a zygote.

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Male gametes and female gametes

Female gamete in plants are called ovules
Male gametes are found inside the pollen grains

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Structure of flower (terms)

Stigma:the part of the flower which receives pollen.
Style:the connection between the stigma and ovary of a flower.
Stamen:the male parts of a flower.
Nectary:a gland producing a sugary fluid,found in many insect-pollinated flowers.
Filament:the stalk of a stamen.
Anther:the part of a stamen in which pollen is produced.
Pollen grains:tough,resistant structures containing the male gametes of a flower.
Pollination:the transfer of pollen from the male part of the flower (anther of stamen) to the female part of the plant (stigma).
Ovary:an organ in which female gametes are made.
Ovule:a structure in the ovary of a flower which contains a female gamete.

Tip:do not use the word ‘flower’ when you mean ‘plant’.a plant is a complete organism but a flower is just part of a plant.

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Wind-pollinated and insect pollinated

Insect-pollinated
1.Large petals
2.strongly scented
3.nectaries present
4.anthers inside flower
5.stigma inside flower
6.spiky pollen grains
7.large quantities of pollen made

Wind-pollinated
1.small petals
2.no scent,no nectaries
3.anthers outside flower,stigmas outside flower
4.light pollen,smooth pollen
5.large quantities of pollen produced

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Self-pollination and cross-pollination

Self pollination:the 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.

Cross-pollination:the transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species.

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Seed germination factors

Water must be present
High temperature
Oxygen

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