reproduction in plants

Making the same of your kind

 

Pollination

  • The transfer of pollen grains from anther to stigma of a flower

 

Types of pollination

  • Self

    • Of the same flower or flower of the same plant

  • Cross

    • Of flower on different plant of same species

    • Needs agents to carry the pollen

 

Effects of cross pollination vs self-pollination

 

 

Cross pollination

Self-pollination

Effects

Brings about variation

  • Offsprings are genetically different

Less variation

  • There is no way the offspring is different from the parent

  • Due to pollen and ovule being genetically similar

  • Disadvantage because if something comes that wipes out that plant, then it could wipe out all the plants

  • It can be beneficial, if those crops grow in a farm. A climate change can favour the growth and it can promote them to survive.

  • The environment plays a role in why there is some sort of variation

 

Offspring can adapt and survive in different environment

Pollinators not required

  • An advantage

 

The need for pollinators

  • Can be a disadvantage because if pollinators are not there then they can't get pollinated

 

 

Fertilisation 

  • Brings the male sex cell normally called the male nucleus

    • From the anther

    • The nucleus is a haploid cell

      • Contains the full set of chromosomes

      • Humans have a diploid of 46

 

  • A male has a diploid of 46

    • The sperm will have a haploid of 23

  • A female has a diploid of 46

    • The egg will have a haploid of 23

  • When the egg and sperm form a zygote it will have a diploid of 46 again

  • If there is a case the number comes back more than 46 it can be down syndrome which this can be considered a mutation

 

  • There should be sufficient moisture and nutrition in the stigma

    • If there is not these, the pollen will disintegrate

      • Trying to allow the growth of the pollen tube

      • Macrocyte opening where pollen tube enters ovule

    • The seed must be viable, if not you can plant as many as you want but you would not get nothing0

  • After fertilisation, the ovule because the seed, and the ovary the becomes the fruit

 

Germination

  • Identify the three factors or conditions necessary for germination

    • Oxygen

    • Water or moisture

    • Suitable or optimum temperature/warmth

  • For each characteristics describe and explain why the condition is necessary

  • Extended

    • How would you

 

  • Pollen grain lands on the stigma

  • Stigma enzymes

  • Pollen grain absorbs moisture and triggers the pollen grain to geminate

    • When it does it grows the pollen tube that grows down the style until it tries to eneter the ovule until it finds an opening

    • The nucleus of the pollen moves along the tube and it enters the ovary and ovule

      • The one opening is called the micropyle

    • The carpel dies off

    • Zygote becomes a seed

 

Reproduction in cells

  • Sexual

    • Combination of genes

    • Meiosis

  • Asexual

    • Replica of genes

    • Mitosis

      • Binary fission

      • You have a parent cell which has a nucleus.

      • Fungi

        • Binary fission

      • Tissue repair

      • Growth and healing

 

 

Normal human cell has 46 chromosomes. These are called somatic or diploid

 

Asexual reproduction in plants

  • Cuttings

    • Cut a branch and stick it in the soil

    • The cells mutate and turn into root cells.

  • Suckers

    • When you have a plant a smaller version of a plant growing on the side

  • Grafting

    • Form of tissue repair

    • Cut a wedge in another plant

    • If joined together, both plants try to heal each other they will grow into each other and become one plant

 

Sexual reproduction

  • We have chromosomes

  • First stage of meiosis is mitosis

  • Homologous chromosomes