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

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

1.small petals 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

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