reproduction and variation. by the end of the lesson, you should be able to: describe asexual...
TRANSCRIPT
LEARNING OUTCOMES
By the end of the lesson, you should be able to:
Describe asexual reproduction.Describe sexual reproduction.Explain why sexual reproduction results in
variation, but asexual reproduction does not produce variation.
Describe differences in characteristics due to genetic or environmental causes or a combination of both.
TYPES OF REPRODUCTION
• There are two very different ways of reproducing:– Asexual reproduction– Sexual reproduction
ASEXUAL REPRODUCTION IN PLANTS
BULBS
Onions Daffodils
Look at the examples of asexual reproduction.
Can you give a definition of the process?
TUBERS
Potatoes
RHIZOMES
Iris
RUNNERS
Strawberry Spider plant
ASEXUAL REPRODUCTION
• No fusion of gametes.• Only one individual is needed as the
parent. • There is no mixing of genetic
information and so no genetic variation in the offspring.
• These genetically identical individuals are known as clones.
Advantages of Asexual Reproduction
Advantages Disadvantages
Asexual ReproductionSexual Reproduction
ASEXUAL REPRODUCTION• Only involves one parent.• Offspring are completely identical to
the parent – clones!• No gametes (sex cells) are needed.• Very safe and easy – no need to find a
partner!• Common in small/simple animals,
plants and bacteria.• Also happens in our body all the time –
to replace worn out or dead cells.• It also happens in some bigger plants.
SEXUAL REPRODUCTION
• Involves the joining (fusion) of the male and female gametes (sperm and egg).
• The mixture of the genetic information from two parents leads to variety in the offspring.
VARIATION
• Genetic Variation• Environmental Variation
Which of the following characteristics are the result of genetic variation, environmental
variation or both?
Gender Weight Hair length
Height Tattoo Eye colour
Hair colour Tongue-rolling Shoe size
Why is variation in a population important?
SEXUAL REPRODUCTION IN PLANTS
• In plants, the eggs are found in ovules (in the ovary of flowers), and the sperm cells are found in pollen.
Pollen grains
FRUIT OR VEGETABLE?
• When the flower has been pollinated, the sperms meet the eggs, and seeds form (the offspring!)
• The ovary turns into the fruit – with seeds inside ready for dispersal.
Which of the following are fruits? Vegetables?
Are they produced by sexual or asexual reproduction?
VEGETABLE!ASEXUAL
FRUIT!SEXUAL
FRUIT!SEXUAL
VEGETABLE!ASEXUAL
FRUIT!SEXUAL
FRUIT!SEXUAL
VEGETABLE!ASEXUAL
SUMMARY
• Fruits always come from a ______.
• Fruits are made through ______ reproduction!
flower
sexual