In your exam you will need an understanding of Unit 6: Inheritance, Variation and Evolution. Here we provide details of some of the key concepts that you could be questioned on when sitting biology paper 2.
The Human Genome
The genome of an organism is the entire genetic material of that organism.
Humans have 23 pairs of chromosomes. One of each set from their mum and one from their dad.
This means that almost every cell in the human body contains 46 chromosomes.
The Human Genome Project
The project helps scientists to search for genes that are linked to different types of disease. This gives us more information on the risk of people developing the disease and might allow us to reduce the risk by encouraging lifestyle changes or interventions.
It helps us to understand and treat inherited disorders. The more we know about faulty genes, the more chance we have at developing treatments to overcome them.
We can use the information to trace human migration patterns from the past. This helps us to understand human evolution and history.
Fossils are the ‘remains’ of organisms from millions of years ago, which are found in rocks. They could take the form of:
- the actual remains of an organism that has not decayed;
- mineralised forms of the harder parts of an organism, such as bones;
- traces of organisms such as footprints or burrows.
An extinction occurs when there are no remaining individuals of a species still alive. This might be due to:
- change in temperature;
- geological changes over time;
- catastrophic event (volcanic eruption, asteroid impact);
- new predators;
- new diseases;
- successful competition from a new species.
- Get more details on fossils and extinction, and access associated tasks in this lesson pack.
Genetic Engineering Advantages and Disadvantages
- Genetically modified (GM) crops have bigger yields and therefore have increased food value. This may help us to address an expanding population.
- Animals and plants grow faster.
- We can mass produce human proteins.
- GM crops can grow in dry, hot, cold or flooded parts of the world. This may help us to manage the effects of global warming on agriculture.
- GM crops can produce their own pesticide, can be resistant to herbicides or can contain specific nutrients.
- Models of human diseases can help us to develop treatments.
- Nobody can be sure of the long-term effects of eating GM food on human health.
- Pesticide-producing crops may result in insects developing resistance to pesticides.
- Genes from GM crops or animals could spread to species in the wild.
- People worry that this may lead to the manipulation of human genes to make ‘designer’ children.
There is variation between individuals in a population.
The individuals in a population compete for food, shelter and mates.
Some adaptations make the individual better at competing.
The individuals with the better adaptations are more likely to survive and reproduce.
When they reproduce, they pass on the alleles for the useful adaptation.
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