Biology

• Species alive today evolved from species in the past.
• Fossils provide really good evidence for evolution.
• 3 ways of fossils forming
• Fossils are the remains of organisms from millions of years ago which are found in rocks.
• 3 ways of fossils can form:

  1. When conditions for decay are absent.
  2. Fossils can form when an organism decays is if parts of an organism are slowly replaced by minerals during decay.
  3. Can be preserved traces (e.g. footprints, spaces where roots were)
• Fossils can form when parts of an organism have not decayed. This can happen when the conditions for decay are absent, for example, if the temperature is too cold, or if there is not enough oxygen or water.
• Fossils can form even if an organism decays if parts of the organism are slowly replaced by minerals during the decay process.
• Fossils can be the preserved graves of organisms. Animals can leave footprints or burrows and plants can leave preserved spaces where roots were.
• Many of the earlier forms of life were soft-bodied organisms. They did not have a shell or skeleton.
• Soft-bodied organisms very rarely form fossils. Many of the fossils that did form have been destroyed by changes to rocks in Earth’s crust. Because there are very few fossils of the early organisms on Earth, scientists cannot be sure how life on Earth began.
• One thing that fossils show is that a huge number of species have become extinct. A species is extinct when there are no remaining individuals of that species still alive.
• A species is extinct when there are no remaining individuals of that species still alive.
• Species can become extinct for several different reasons.

  Species can become extinct due to a catastrophic event (for example asteroid - dinosaurs).

  When the environment changes (for example, changing weather patterns).

  A new disease/predator.

  A new successful species evolves and competes with them for survival and success. (for example for scarce food or water).
• Reasons species could go extinct are catastrophic event, environment changes, new disease/predator, and if a more successful species evolves and competes with more success.
• Charles Darwin’s theory of natural selection proposed that all species have evolved from simple life forms that first appeared on Earth more then 3 billion years ago.
• The process is:

  • Genetic variation - Different individual animals in a population (or species) have different combinations of genes
  • Survival of the fittest - Insividual
• Since genetic engineering is a relatively recent development, it is uncertain what the long-term effects may be.
• Are resistant to all diseases - NOT an advantage of genetically modified crops
• Some people expect GM (genetically modified) crops to negatively impact wild flower and insect populations, thus reducing biodiversity.
• Genetically modified crops may have disadvantages for:

  • Human health
  • Biodiversity
• Food miles - Diet shifts in developed countries are resulting in the accumulation of a massive quantity of food miles. This is because food is transported across the world in order to meet demands.
• Food security will be achieved when the whole global human population has access to enough safe and nutritious food to stay healthy. Currently, the most pressing obstacles to this goal are: (1/3)


  1. Conflicts - often result in reduced access to food and water
  2. Diet shifts

  • Diet shifts in developed countries are resulting in the accumulation of a massive quantity of food miles.
  • This is because food is transported across the world in order to meet demands.
• Food security will be achieved when the whole global human population has access to enough safe and nutritious food to stay healthy. Currently, the most pressing obstacles to this goal are: (2/3)

  3) Birth rates - Increasing birth rates, especially in sub-Saharan Africa.

  4) Extreme meteorological events - The increase in the frequency of extreme meteorological events associated with climate change.
• Food security will be achieved when the whole global human population has access to enough safe and nutritious food to stay healthy. Currently, the most pressing obstacles to this goal are: (3/3)

  5) Cost of agricultural inputs

  • Agricultural inputs, such as fertiliser, are essential for ensuring that food is produced at sufficient yields.
  • Their increasing price means farmers can afford less and yields suffer.

  6) New pests and pathogens - reduce farming yields.
• Food security - This is achieved when the whole global human population has access to enough safe and nutritious food to stay healthy.
• Biotechnology is the use of biological processes to develop or make products.
• Golden Rice - This food source has been genetically modified to contain a molecule that helps make Vitamin A.
• Mycoprotein - Produced by growing the fungus Fusarium, this food source is high in protein and fibre, low in fat and suitable for vegetarians.
• Qualities of mycoprotein - High in protein, high in fibre, low in fat, suitable for vegetarians
• Farming Techniques for Improving Food Productions

  To ensure global food security is achieved, it is essential that the efficiency of food production is improved: (1/2)

  1. High protein foods - Feeding animals foods that are high in protein helps boost their growth rates.
  2. Food Chains - Only about 10% of energy passes from each trophic level to the next. Therefore, shortening food chains will greatly increase efficiency.
• Farming Techniques for Improving Food Productions

  To ensure global food security is achieved, it is essential that the efficiency of food production is improved: (2/2)


  3) Livestock - Energy will always be transferred from livestock to the environment due to essential processes, like moving or maintaining body temperature. Limiting the amount of energy wasted in this way helps improve food production efficiency.
• • As populations have grown farming practices have become more intensified to maximise group yields and ensure that we can feed our ever-growing population.
  • Fertilizers and pesticides are used on crops
  • Animals may be kept in more densely packed sheds to maximise milk yields or egg production or speed up the time needed for the animal to be ready to be sent to the market
• Farming Techniques For Improving Food Production Include:

  1. Shorten food chains
  2. Limiting energy transfer to the environment
  3. High protein foods
• How do high protein foods benefit animals?


  Boost growth rates
• Farming Techniques for Improving Food Production

  Most human food comes from a small number of crops: cereals, potatoes, root vegetables and legumes (such as lentils). (1/4)


  Biological Control

  • A crop's pest can be reduced or eliminated by introducing a natural parasite, predator or pathogen (disease) of the pest.
  • For example, the glasshouse whitefly pest has been successfully controlled with a parasite wasp.
• Farming Techniques for Improving Food Production

  Most human food comes from a small number of crops: cereals, potatoes, root vegetables and legumes (such as lentils). (2/4)

  • Biological Control (2/2)
  • This is a good solution because the biological control is specific to the pest, and the pest does not become resistant (like it might to pesticide chemicals).
  • But the control itself can become a pest (like cane toads in Australia, which were introduced to eat beetle pests).
• Farming Techniques for Improving Food Production

  Most human food comes from a small number of crops: cereals, potatoes, root vegetables and legumes (such as lentils). (3/4)

  Crop Strains - Farmers may choose to grow crop strains that have a higher yield or are more disease-resistant than other strains.

  Fertilisers (1/2):

  • Adding fertilisers to crops increases growth rates when minerals (such as nitrates) are the limiting factor and can make infertile soil fertile (allows plants to grow in it) again.
  • But weeds can also grow faster when fertilisers are added.
• Farming Techniques for Improving Food Production

  Most human food comes from a small number of crops: cereals, potatoes, root vegetables and legumes (such as lentils). (4/4)

  Fertilisers (2/2):

  • The fertilisers can also leak into the surrounding environment and contaminate water sources.

  Reducing Competition:

  • Pesticides (kill insect pests), fungicides (kill fungi) and herbicides (kill weeds) reduce competition for resources.
  • But these are often toxic and can cause harm to the environment.
• Increasing Crop Yield:

  • Fertilisers
  • Pesticides
  • Crop Strains
  • Biological Control
• What possible disadvantages are there to using pesticides to increase crop yield?


  • Many pesticides, such as DDT, are toxic to other species as well as to the pest.
  • Pesticides can build up in a food chain, and reach deadly levels in predators.