Producer & Consumers All organisms in our world are connected to each other & termed Producers Consumers

Producers Producers make their food by a process called photosynthesis.

Food Chain The way in which organisms interact can be shown by a food chain.

Food Chains The arrows show the direction of energy flow.

(secondary consumer) (primary consumer) The 1st consumer is called the primary consumer The 2nd consumer is called the secondary consumer

Energy loss in Food chains Only 10% of energy is passed on to next level in a food chain.

Energy loss in Food chains Most of the energy is lost as: A) Heat B) Movement C) Undigested material

Calculation 1000 units of energy in grass – how much energy does the owl receive?

Calculation 1000 units of energy in grass – how much energy does the owl receive? 1000 100 10 1

Key word Definition Consumer Omnivore Carnivore Herbivore Prey Eats another organism Omnivore Eats animals and plants Carnivore Only eats other animals Herbivore Only eats plants Prey Gets eaten by the predator Predator Feeds on the prey Producer Makes its own food by photosynthesis

Food webs Animals usually eat many different things and are involved in lots of different food chains. These more complicated feeding relationships can be shown in a food web.

Analysing food webs What would happen to the _________ if the ________ died out? Increase or decrease – why?

Fiercer Interspecific vs. Intraspecific There is a lot of competition for resources among organisms in a food web. Fiercer Interspecific vs. Intraspecific Between organisms of different species for similar resources. Between organisms of the same species for the same resources.

There is a lot of competition for resources among organisms in a food web. Animals compete for... Food Mates Habitats Plants compete for... Nutrients Water Space

1. Pyramid of Energy BLACKBIRD LADYBIRD GREEN FLY ROSE BUSH Shows the total energy received by organisms at each stage of a food chain

2. Pyramid of Numbers Show the total number of organisms at each stage of a food chain. Small numbers of large organisms 1 fox 30 Rabbits 100,000 blades of grass Large numbers of small organisms

Problems with Pyramids of Numbers What if tree is the producer? Oak tree greenfly wasp blue tit What if insects are the top consumer? Grass zebra lion flea

Pyramid of numbers = not always a pyramid! Oak tree Greenfly Finch Pyramid of numbers = not always a pyramid!

Biodiversity Variety and abundance of all living organisms. Importance of biodiversity; Variety of organisms is important so that they can adapt to changing environment conditions.

Habitat Community Where the animals/plants live. All the organisms living together.

An area made up of living & non living parts. Population The number of ONE species living in an area. Ecosystem An area made up of living & non living parts.

Factors affecting biodiversity 1. Biotic 2. Abiotic (living) (non-living)

Biotic factors Living factors affecting biodiversity; Predation Grazing Disease Competition Food availability

Predator/Prey Graphs

Abiotic factors Non-living factors affecting biodiversity; Temperature Light intensity pH Moisture

Sampling Techniques Techniques used to measure various biotic and abiotic factors in the environment. Animals Pitfall traps Tree beating Plants Quadrats

Quadrats Thrown at random (not placed down). Don’t count number of flowers, count number of squares the flower is in. Repeat for increased reliability.

Errors with quadrats Not thrown randomly (throw randomly) Organisms wrongly identified (use key)

Pitfall Trap (e.g. woodlouse) Hole dug level with ground. Covered with stones, leaves. Checked regularly.

Errors with pitfall traps Hole not level with ground – insects won’t fall in. Trap not hidden – insects will avoid the trap. Not checked regularly – insects could eat each other.

Abiotic sampling techniques Light intensity Moisture pH Temperature

Light intensity Measured with a light meter. Hold the light meter arms distance away so that you don’t cast a shadow over it. Point at maximum light.

Errors with light intensity Accidentally shading the light meter.

Moisture or pH Measured with a moisture meter/pH meter. Push the probe into the soil and read the meter.

Errors with moisture or pH Not wiping pH meter/moisture meter probes between readings.

General rule; Results are made more reliable by taking many samples (REPEATING experiment).

Identifying Organisms It’s all very well counting/collecting organisms, but not all of them will be familiar to us. To identify unfamiliar organisms, we would use a key. There are different kinds of key.

Branching Key Animals Legs No legs 8 legs More than 8 legs Shell No shell Snail Earthworm Spider Centipede

Paired Statement Keys Paired statement keys work in the same way as branching keys. At each stage you are given a choice. Make the appropriate choice and go to where you are asked to go. Again, if the organism is present, you should end up with a name for it.

Mutation Random Change to DNA bases. Mutations are: Randomly Occurring Low frequency (ROLF)

Mutation Types 1. Disadvantage (genetic disease) 2. Advantage (new variety of species) 3. Neutral

3 copies of chromosome 21 (instead of just 2). Genetic Disease: Down Syndrome 3 copies of chromosome 21 (instead of just 2). Occurs in 1 in every 1,000 children born each year.

Advantageous Mutations Mutations create variety (new alleles). Variation helps animals or plants cope with environmental change.

Example: Peppered moth

E.g. different coloured eyes Neutral Mutations Changes in DNA bases that are neither beneficial nor detrimental to the ability of an organism to survive and reproduce. E.g. different coloured eyes

Mutagenic Agents Increase the frequency of a mutation occurring. Examples include; X-rays UV radiation Mustard gas High temperatures

1. X-rays

2. UV radiation

3. Mustard gas

Adaptations Mutations (increased variety) allows organisms to adapt to be better suited to their environment/cope with environmental change.

Adaptations of the desert rat Burrowing into sand when temperature is too high. Large back feet help them to jump away from predators. Behavioural Structural

Adaptations of the cactus The leaves are reduced to spines in order to decrease the surface area for water loss. Vast root system to maximise water uptake. Structural

Adaptations of the camel Rest during the day when the temperatures in the desert are very high. Humps store fat which produces water when metabolised. Behavioural Structural

The theory of evolution states that evolution happens by natural selection. Key points: Individuals in a species show a wide range of variation. Individuals with characteristics most suited to the environment are more likely to survive and reproduce. The genes that allowed the individuals to be successful are passed to the offspring in the next generation.

“Survival of the fittest” Darwin’s Theory of Evolution “Survival of the fittest”

The organism best suited to the environment survive. Natural Selection The organism best suited to the environment survive.

Natural Selection There is natural variation in the population.

Natural Selection Those with the selective advantage for survival increase in population.

Natural Selection These organisms are able to breed and pass on their desirable genes.

Natural Selection Organisms without the selective advantage die out.

Likely exam question! Q. Explain the concept of “survival of the fittest”. (2) Natural Selection chooses organisms that have a SELECTIVE ADVANTAGE for survival who then reproduce & pass on successful alleles.

What is a species? A group of related organisms that interbreed & produce fertile offspring.

Horses and donkeys are closely related, and look very similar, but they are members of different species. Horses mate with each other to produce young horses, which themselves will be able to mate (fertile).

Donkeys can mate with each other to produce young donkeys, which themselves will be able to mate (fertile).

If a donkey mates with a horse, they produce a mule, which is infertile and cannot mate to produce offspring. Fertile Fertile Infertile

Speciation Creating a new species.

Speciation – 3 stages 1. Isolating Mechanism 2. Mutations 3. Natural Selection New species formed!

One species of organism.

The species is split into 2 sub-populations, separated by an isolating mechanism. The isolating mechanism prevents gene flow across sub-populations.

Mutations (low frequency) occur on either side of the barrier.

Natural Selection chooses organisms that have a selective advantage for survival, who then reproduce & pass on successful alleles.

A new species is formed. This new species cannot interbreed with the original species to produce fertile offspring (even if the barrier is removed).

Types of Isolating Mechanisms Geographical Ecological Reproductive

Importance of isolating mechanisms Prevents gene flow (exchange of genes) between sub-populations. 2 3 4 Free flow of genes between all population Population 3 becomes extinct Population 4 becomes isolated 1 Flow of genes only 1 to 2

How many species?

How many species? Isolating mechanism

Common error in ‘isolating mechanism’ answer “the barrier separates different species”. Barriers separate groups of the same species, which then undergo mutation and natural selection until they become separate species.

I’m a new species. Speciation! Quick recap… Just remember…… 1. Isolation 2. Mutation 3. Natural selection Speciation!

Food Science Challenge What’s the problem? Not enough food to feed everyone. Food Science Challenge Need to increase yield of crops grown.

Solution? Intensive Farming 2. Biological Control 3. Genetically Modified (GM) Crops

Advantages of Intensive Farming Increased yield making food more affordable/available.

Features of Intensive Farming Fertilisers Nutrients to help crops grow (nitrates). Pesticides To kill pests that eat crops.

Problems with pesticides Pesticides aren’t broken down, so they build up at each stage of the food chain. This can be toxic for the predators at the top of the food chain.

Problems with fertilisers Creates algae bloom in water.

Disadvantage of fertilisers 1. Fertiliser washes into rivers from fields. 2. Increased algae bloom. 3. Increased bacteria as they feed on algae. 4. Decreased oxygen levels (all the bacteria use the oxygen for respiration). 5. Decreased biodiversity.

Intensive Farming Summary 1. Algae bloom Deoxygenates water as bacteria that feed on algae use up oxygen and reduce biodiversity. 2. Pesticide build up (DDT) DDT builds up to toxic levels in food chains. Pesticide resistance.

Indicator Species A species whose presence/absence indicates level of pollution in environment. Lichen only grows where there is little air pollution (little SO2).

Indicator Species Example Stone fly nymph Only present in high oxygen levels in water (no algae bloom).

Biological Control Natural method of control (no chemicals). a) Using predator b) Deliberately introducing a disease

Advantages 1. No chemicals so no algae bloom/pesticides building up. 2. Cheap after initial set up costs.

Disadvantages 1. Can’t guarantee that all pests will be killed. 2. Predator or disease could become the problem in place of the pest.

Genetic Engineering (Cell Biology unit) A useful gene from another species is inserted into the plant to produce a GM crop.

Examples of GM crops Golden Rice with added nutrients. Tomatoes with a longer shelf life. Disease resistant potatoes.