Unit 3

• Food security is a populations access to food of sufficient quality and sufficient quantity
• Plans for food security should be sustainable. This means it should not cause irreparable damage to ecosystems and continue for a long time.
• Anything that affects the rate of photosynthesis will affect food availability. if we remove limiting factors, we can increase the rate of photosynthesis which will increase crop yield.
• a high yielding cultivar is a breed of crop plant that is designed for a particular purpose. Increases crop yield
• Pests are organisms that eat crop plant. If leaves are eaten, this results in less surface area for the plant to absorb light. Decreases crop yield. we can use insecticide to minimise impact.
• Weeds compete with crop plants for resources. Decrease crop yield. Can use herbicides to minimise damage
• Crops produce more energy per unit area than livestock due to energy loss between trophic levels.
• Light energy comes mostly from the sun. Can be Absorbed, Reflected or transmitted
• thylakoid contains photosynthetic pigments
• Primary pigment- Chlorophyll a, absorbs red and blue light
• Accessory pigments- Chlorophyll b, absorbs blue and red. Carotenoids- Carotene and Xanthophyll- extend the range of wavelengths of light absorbed by the plant
• Absorption Spectrum- shows how much light is absorbed by each wavelength of light.
• Action Spectrum- the rate of photosynthesis at each wavelength of light
• Light Independent reactions- takes place in thylakoid.

  1. Light energy is absorbed by chlorophyl.
  2. Electrons in chlorophyll gain energy and move along ETC.
  3. Energy is also used to split water into hydrogen and oxygen (photolysis)
  4. Hydrogen ions pumped into thylakoid using energy from ETC
  5. Hydrogen ions diffuse out thylakoid through ATP synthase allowing it to generate ATP
  6. Hydrogen ions and electrons are combined to form NADPH
  7. ATP and NADPH are passed onto next stage
• Light Independent Reactions- AKA Calvin Cycle

  1. Carbon dioxide enters cycle attatching to RUBP to form 3-PG. Controlled by emzyme RUBISCO
  2. 3PG combines with hydrogen (provided by NADPH) and phosphorylated by ATP to form G3P.
  3. Some of the G3P is used for the synthesis of glucose, some to regenerate RUBP. Sugars produced by G3P can be used as respiratory substrates, synthesised into starch or cellulose or passed onto other metabolic processes
• The aim of breeding plants and animals is to produce high yielding cultivars.
• Factors we want in plants:

  • disease resistant
  • large growth
  • pest resistant
  • good at photosynthesis
  • high nutrient content
  • drought resistant

  We can achieve these through selective breeding or genetic modification.
• Factors we want in animals:

  • disease resistant
  • large growth (muscle mass)
  • high egg or milk yield
  • reduction in methane production
  • high nutrient content
  • reproductive success

  We can achieve this through selective breeding or genetic modification
• Field trials - experiments that allow us to test the effectiveness of new cultivars by comparing them to standard crop, test new treatments and compare GM crops to non GM crops
• Selection of treatment - only change one thing, control as much as we can
• Number of replicates - each treatment should be used more than once
• “Randomisation of treatments” - helps account for factors we cannot control “eliminates bias”
• Inbreeding - breed closely related individuals that share the desired characteristics to create breeds that run true. True breeding organisms are homozygous for the desired allele
• Inbreeding depression- increase in frequence of individuals that are homozygous for deleterious recessive alleles. this will decrease the fitness of these individuals and lower their ability to reproduce.
• We can use genome sequencing to identify individuals with the genes for desired traits so they can be used for selective breeding
• Weeds

  • produce chemicals that reduce plant growth/germination
  • seeds from weed plants can contaminate harvest
  • act as vectors of disease

  Annual weeds- short lived, grow quickly, produce large amounts of seeds.

  Perennial weeds- long lived, deep storage organs, reproduce by vegetative propagation.
• Herbicides

  Contact Herbicide- kill any part of plant they come jn contact with.

  Selective Herbicide- more effect on broad leaved plants.

  Systematic Herbicide- travels through plants vacular system to reach all parts of parts of plant and prevents regrowth.
• Systematic pesticide- travel to all parts of plant and kills any pests that eat any part of the plant.
• Fungicides- kill fungal spores that land on crop, should only be sprayed according to disease forecast.
• Biological Control- introducimg a natural predator, pathogen or parasite of the pest in order to control its population.
• Integrated pest management- using a combination of Biological, Chemical and Cultural control methods to control pest populations
• Intensive farming

  + cheap

  + more food

  -doesnt meet welfare needs

  -more suspceptible to disease

  -PR issue
• Free Range Farming

  + healthier happier animals

  + PR good

  + better quality of food produced

  -more expensive

  -animals can pick up diseases or be predated on

  -consumers need to eat less meat
• Poor welfare can be shown through behavioural indicators:

  • Stereotypy- excessive repetitive behaviour.
  • Misdirected behaviour- natural behaviour directed at something other than it would naturally.
  • Failure in sexual or parenting behaviour- not being able to reproduce, abandoning or mistreating offspring.
  • Altered levels of activity- Very low (apathy) or very high (hysteria) levels of activity.
• Symbiosis- interspecific interactions between individuals of different species.

  • result of coevolution- adaptions in one species that act as selection pressures on the other.
• Facultative parasites- can survive seperate from their host, tend to be external parasites.
• Obligate parasites- cannot survive without a host, tend to be internal parasites, have a limited metabolism so they rely on their host
• parasites are transmitted by:

  • Direct contact
  • Resistant stages- can tolerate environmental conditions until a new host is available.
  • Vector- passed from one host to another by another organism. Can act as secondary hosts for the parasite.
• Mutualism- interaction that provides a benefit to both partner species.
• When organisms live in social groups there is an increase in competition for resources so an increase in conflict.

  Overcome this by using a social heirarchy where there are dominant and subordinate individuals in the group and they are aware of their ranks.

  To reduce Conflict dominant individuals use ritualistic displays (teethbarimg, hissing) amd subordinates respomd with appeasement behaviours (rolling over, bowing)