GCSE OCR B2 Revision

• Largest animal group
• Have an exoskeleton that sheds as they grow
• Have limbs with joints that allow the Arthropods to move
• Subdivision of invertebrate

Animals - Elephants, Llamas, Frogs etc

No cellular walls, Multicellular

Plants - Trees, Flowers, Magical talking shrubberies etc

Cellulose wall, Use light to produce food by photosynthesis

Fungi - Mould, Smurf's mushrooms, Yeast etc

Chitin cell walls, Reproduce using spores

Prokaryotes - Blue/Green algae, Bacteria

Cells have no nucleus, Cell wall isn't made from cellulose

Protoctists - Amoeba, Paramecium, Protoza (Don't worry, I don't know what they are either)

Single cell organisms, Colony of single cells

Biomass means the dry mass of living material at a stage in a food chain. The biomass goes down from one stage to the next, just like the amount of energy.

Each stage in a food chain/pyramid of biomass, is called a trophic level. It can be differcult to make a Pyramid of Biomass because:

• An organism may belong to more than one trophic level, so it cannot easily be represented by one bar.
• There may be problems whilst measuring the dry mass (You can't get the dry mass of a living creature easily)

Binominal system - Organisms are given 2 latin names (Genus & Species)

Species - Group of organisms that can interbreed to produce fertile young

Artificial Classification - Based on observed characteristics. Used for simplicity, say what you see.

Natural Classification - Includes natural relationships. Internal & external features ased on evolutionary relationships and DNA.

Lion + Tiger = Liger. This is NOT a species as it cannot produce fertile young.

Kingdom                    Going up the list, Increasing number of species in each group
Phylum
Class
Order
Family                       Goin down the list, Increasing in simularity.
Genus
Species 

• Not everything fits
• Infertile hybrids can be produced by breeding members of different species
  (e.g. Horse + Donkey = Mule)
• Evolution is a continuing process
• Bacteria can reproduce asexually and so cannot be classified into a species
• Not all species that look the same evolved from common ancestors back have adapted to live in the same environment so share characteristics. 
  (e.g. Whales, Dolphins and Sharks all look the same but have evolved from different ancestors) 

MRS NERG (Ugly name but she's a fittie)

M ovement
R eproduction
S ensitivity

N utrition
E xcretion
R epiration
G rowth

(1) Engery from the Sun is used during Photosynthesis
(2) Green plants are producers because they produce biomass. Other producers include algae and plankton
(3) Energy is used for MRS NERG along the food chain so there isn't much left over.
(4) Only 10% of energy is passed on to the next trophic level due to heat, respiration and waste products. Not all parts of the animal is digested.

Energy Efficiency = (Energy converted to Biomass/Total energy taken in) x100 

Trophic Level - Each level or stage that something occupies in the food chain

Omnivore - Eats both plants & Animals (Omnomnomivore eats all da food)

Herbivore - Eats only plants (Not just herbs)

Carnivore - Eats only animals (LIKE A HUUUUGE T-REX RAWR)

Producer - Makes its own food in the food chain. Usually by photosynthesis

Primary answer - Eats the producer and animals (Not like the producer of a film)

Secondary answer - Eats the primary consumer. Usually a carnivore but sometimes an Omnomnomivore

The two main types of competition are:
Interspecific competition - Which happens between individuals of different species
Intraspecific competition - Which happens between individuals of the same species

A niche is a particular place or role occupied by an organism within an ecological community. Similar species will occupy similar niches. For example, red squirrels and grey squirrels are two different species. They occupy similar but slightly different niches.

Habitats have limited amounts of the resources needed by living organisms. Organisms must compete with others in order to get enough of these resources to survive. If they are unsuccessful and cannot move to another habitat, they will die. (Don't have sex 'cause you'll get pregnant and die)

Animals might have to compete for mates so they can reproduce. They also compete for: Water, Space, Food

Plants make their own food using photosynthesis, so they don't compete for food. They may have to compete for: Water, Light, Minerals.

In mutualism, both species benefit from their relationship. For example, Oxpecker birds eat ticks and larvae infesting the skin of Buffalo and other large animals. For this reason, Oxpeckers are called a cleaner species.

Lichens are another example of mutualism They are formed by algae and fungi living together (IN PERFECT HARMONYYYYYY) Algae can photosynthesise and make food, which is shared by the fungus. The fungus in turn shelters the algae from a harsh climate.

A tapeworm lives inside another animal, attatching itself to the hosts' gut and absorbing its food. The host loses nutrition and may develop weight loss, diarrhoea & womiting. Parasites do not usually kill the host, as this would cut off their food supply.

Parasites are organisms that live on or in a host organism. The parasite benefits from this arrangement, but the host suffers as a result. Fleas are parasites. They live on the skin of other animals and **** their blood. This feeds the flea but weakens the host.