SEXUAL AND ASEXUAL REPRODUCTION (+ADV/ DISADV)

• SEXUAL REPRODUCTION:

  • Occurs in ANIMALS / flowering PLANTS
  • FUSION of MALE and FEMALE gametes via FERTILISATION
  • Mixing of GENETIC INFORMATION from MALE and FEMALE
  • Each GAMETE is different- OFFSPRING are genetically DIFFERENT (causes VARIATION)
• In flowering plants:

  • Male and female gametes are the EGG and POLLEN cells
• In humans:

  • Male and female gametes are the EGG and SPERM cells
• ASEXUAL REPRODUCTION:

  • APHIDS reproducing, certain PLANTS
  • ONE parent so no GAMETES
  • No MIXING of genetic INFORMATION so genetically IDENTICAL offspring called CLONES
  • No MEIOSIS, only MITOSIS
• ADVANTAGES OF SEXUAL REPRODUCTION:

  Offspring is genetically DIFFERENT- causes VARIATION

  • SURVIVAL advantage by NATURAL SELECTION
  • Challenging CONDITIONS, greater chance of SURVIVAL
  • Natural SELECTION can be SPEEDED up by HUMANS in selective BREEDING to increase FOOD production (high YIELD , QUALITY of foods)
• ADVANTAGES OF ASEXUAL REPRODUCTION:

  ONE parent needed- so no need to look for a MATE

  • Therefore TIME and ENERGY efficient

  FASTER process than sexual reproduction

  • USEFUL when conditions are FAVOURABLE, can produce genetically IDENTICAL offspring RAPIDLY
• DISADVANTAGES OF ASEXUAL REPRODUCTION:

  Asexual reproduction is RISKY

  • Offspring are genetically IDENTICAL
  • Therefore the offspring could all DIE if conditions are UNFAVOURABLE
• Some organisms reproduce by both methods depending on the circumstances:

  Malarial parasite:

  • In Human HOST- ASEXUAL reproduction, In mosquito VECTOR- SEXUAL reproduction

  Fungi:

  • ASEXUAL reproduction by SPORES
  • Also use SEXUAL reproduction to give VARIATION

  Plants:

  • SEXUAL reproduction to produce SEEDS
  • ASEXUAL reproduction by: RUNNERS in STRAWBERRY plants, bulb DIVISION e.g. DAFFODILS