4.8 Reproduction

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  • Created on: 12-05-19 12:19

Asexual and Sexual reproduction

  • Asexual reproduction
    • involves mitosis
    • involves one parent
    • offspring have identical genes to parent
    • so no variation in offspring
  • Sexual reproduction
    • involves meiosis
    • involves the fusion of male and female gametes - this creates a zygote that undergoes cell division to develop into an embryo
    • involves two parents
    • so offspring has a mixture of parents' genes
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Asexual and Sexual reproduction in Plants

  • Insect pollinated plants:
    • have brightly coloured petals - to attract insects
    • have scented flowers and nectaries - to attract insects
    • make big, sticky pollen grains - so that they stick to insects as they go from plant to plant
    • the stigma is sticky - so that pollen picked up by insects on other plants will stick to it
  • Wind pollinated plants:
    • have small dull petals - as they don't need to attract insects
    • have no nectaries or strong scents - for the same reason
    • have a lot of pollen grains that are small and light - so that they can be carried by the wind
    • have long filaments that hang anthers outside the flower - so a lot of pollen gets blown away by the wind
    • have a large feathery stigma to catch pollen as it is carried by the wind - it often hangs out the flower too
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Germination of seeds

  • Seeds lie dormant until the conditions around it are right for germination. These would be:
    • Water - to activate enzymes that break down the food reserves in the seed
    • Oxygen - for respiration, which transfers energy from food growth
    • Temperature - for the enzymes inside the see to work; it depends on what type of seed it is
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Female Reproductive System

  • Ovaries - produce eggs and female hormones (oestrogen & progesterone)
  • Fallopian tube - carries egg from ovaries to womb; fertilisation takes place here
  • Uterus - thickened lining for implantation of embryo
  • Cervix - narrow opening of womb/uterus
  • Vagina - sperm are deposited here during sexual intercourseImage result for womb
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Male Reproductive System

  • Testes - produce sperm and make male hormones (testosterone); they are held in the scrotum to maintain a low temperature
  • Sperm duct / VAs deferns - carries sperm from testes to urethra
  • Prostate gland & Seminal vesicles - produce fluid that mixes with sperm to make semen
  • Penis - contains erectile tissue which fills with blood; used to deposit sperm during sexual intercourse

Image result for male reproductive system

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Pregnancy

  • Once the egg has been fertilised, it develops an embryo and implants in the uterus. The embryo is called a fetus in later stages of pregnancy.
  • After the embryo is implanted, the placenta develops - this lets the blood of the embryo and mother get very close, to allow exchange of food, oxygen and waste.
  • Then the amnion membrane forms - this surrounds the embryo and is full of amniotic fluid. Amniotic fluid protects the embryo against knocks and bumpsRelated image
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