Detailed Notes on Module 5 Heredity

1. How does reproduction ensure the continuity of a species? 

Occurs by many land mammals

Eg. reptiles, mammals & birds

Advantages

• Increased possibility of the union of gametes (due to contained environment)
• Higher birth rate as the baby grows inside
• More selective of mates (internally)

Disadvantages

• Time must be spent trying to attain a mate
• Increased energy must be used to fuse gametes

Both male and females release the sex cells into the surrounding environment (in water) 

Eg, Fish & amphibians

Advantages

• Generally a large number of offspring come out of this
• More genetic variation
• Easier to fertilise as they don’t need to mate

Disadvantages

• Fusion of gametes may not occur
• Has to occur in water
• Decreased chance of fertilisation/survival due to the possibility of them dying

• Involves fusion of genetic material which is the combination of two parents to form an offspring causing high genetic variation – use of meiosis 
• Process of Pollination – insects, birds or wind carry pollen (male sex gamete) from a flower to another
• The pollen attaches to the stigma where the the fusion of the two gametes causes a seed to grow where the ovules once were > grows into a fruit

• Offspring created is identical as it comes from one parent – use of mitosis 

Types of asexual repro in plants

• Runners – side branches with clumps of leaves and roots which grow on the ground, the roots dig down and establish the plant as its own individual plant, ie. Strawberries
• Bulbs – bulbs are underneath certain plants which allow buds to grow from them and then flourish their own individual plant eg. daffodil
• Cutting – branch off a tree is cut and stripped down, then is planted again to grow as its own individual plant