1_Biology (B2)

1. Human cells: Remember the acronym for whats in this cell... Nice Chicken Curry Mild Rice

   Annotations:

   • Use this acronym to remember what is in a human cell: Nice Chicken Curry Mild Rice
   1. Nucleus (controls the cells activities)

      Annotations:

      • Controls the cell's activities
   2. Cytoplasm (where all the chemical reaction take place)

      Annotations:

      • Many chemical reactions take place.
   3. Cell membrane (controls the movements of substances in and out of the cell)

      Annotations:

      • Controls the movement of materials in and out of cell.
   4. Mitochondria (release energy during aerobic respiration)

      Annotations:

      • Energy is released during aerobic respiration
   5. Ribosomes (where protein synthesis takes pace)

      Annotations:

      • Protein synthesis takes place
2. Plant cells: contains everything in a animal cell with these extra...

   Annotations:

   • Contain all the things in a human cell, with these extra:
   1. Cell wall (made of cellulose for support)

      Annotations:

      • Made of cellulose for support
   2. Chloroplasts (contains chlorophyll for photosynthesis. It absorbed light energy to make food)

      Annotations:

      • Contain chlorophyll for photosynthesis. The light energy is absorbed to make food.
   3. Permanent vacuole (contains cell sap)

      Annotations:

      • Contains cell sap

Annotations:

• -Very small and can only be seen by a microscope.

1. Bacteria

   Annotations:

   • Contains a cell membrane and cytoplasm surrounded by a cell wall.
   • NO NUCLEUS - genetic material is in the cytoplasm
   • Multiplied bacteria = bacterial colony
   1. Contains a nucleus, cell membrane and cytoplasm surrounded by a cell wall
   2. Has no nucleus the Genetic material is drifting in cytoplasm. It has plasmids (small circular bits of DNA) carry extra bits of information. it has Flagella to help it move around and a slime capsule which is on the outside of the cell membrane and cell wall
2. Yeast

   Annotations:

   • -SINGLE-CELLED organism -Have a nucleus, cytoplasm and a membrane surrounded by a cell wall.
   1. Single celled organism. Has a nucleus, cytoplasm and a cell membrane surrounded by a cell wall

Annotations:

• The spreading out of the particles of a gas, or of any substance in a solution.

1. Concentration

   Annotations:

   • NET MOVEMENT into or out of cells depends on concentration on either side of cell membrane.
   • Difference in concentration between two areas is: CONCENTRATION GRADIENT
   1. NET MOVEMENT into or out of cells depends on concentration on either side of the cell membrane. the difference in concentration between two areas is called the CONCENTRATION GRADIENT.
2. Increasing diffusion

   Annotations:

   • Rate is increased when: -Distance is decreased. -Surface area is increased. -Concentration gradient is increased.
   1. Rate of diffusion is increased when: - distance is decrease -surface area is increase - concentration gradient is increased
3. Examples

   Annotations:

   • Diffusion of oxygen into cells of body from the bloodstream. Due to respiration of cells.
   • Diffusion of carbon dioxide into actively photosynthesizing plant cells.
   • Diffusion of simple sugars and amino acids from gut through cell membranes.
   1. Diffusion of oxygen from bloodstream into cells due to the respiration of cells
   2. Diffusion of carbon dioxide into actively photosynthesizing plant cells
   3. Diffusion of simple sugars and amino acids from gut through cell membranes
4. The spreading out of the particles of gas, or of any substance in a solution

1. Tissues: A group of cells with similar structure and functions

   Annotations:

   • A tissue is a group of cells with similar structure and function.
   1. Animal tissues

      Annotations:

      • Muscle tissue - Can contract to bring about movement.
      • Glandular tissue - To produce substances such as enzymes or hormones.
      • Epithelial tissue - Covers some parts of the body.
      1. muscle tissue- can contract and relax to bring movement
      2. Glandular Tissue- produces substances such as enzymes and hormones
      3. Epithelial Tissue- covers some parts of your body
   2. Plant tissues

      Annotations:

      • Epidermal tissue - Covers the plant
      • Mesophyll - Can photosynthesize
      • Xylem and phloem - transport substances around the plant.
      1. Epidermal tissue covers plant
      2. mesophyll tissue can photosynthesize
      3. xylem and phloem-transport substances around the plant like veins
2. Organs: a group of several tissue types

   Annotations:

   • Organs are made of several tissue types.
   1. The stomach

      Annotations:

      • The stomach is an organ made up of: -Muscular tissue to churn the stomach contents. -Glandular tissue to produce DIGESTIVE JUICES. -Epithelial tissue to cover the outside and the inside of the stomach.
      1. Made up off muscular tissue (to churn the contents), Glandular tissue (to produce digestive juices) and epithelial tissue (to cover the inside and outside of the stomach)
   2. Organ System
      1. Group of organs working together to create a organ system
         1. The Digestive system
            1. The digestive system is adapted to exchange substances with the environment. consists of 5 organs

1. - cells are specialized to carry out particular function. - the structure of the cell gives clues to its function
   1. Muscle cells
      1. needs lots of mitochondria to create lots of energy
   2. Gland cells
      1. Needs lots of ribosomes to create lots of protien
   3. Neurons
      1. Specialized to carry impulses from receptors to the CNS

Annotations:

• During photosynthesis, light energy is transferred to chemical energy.
• Some of the glucose is converted into insoluble starch for storage.

1. Testing for starch

   Annotations:

   • -Testing leaves with iodine solution, to test for starch.  -Green patches will turn solution blue-black to show starch has been made.
   1. Boil leaf for 10 min. place in ethonol. add iodine. if it goes black or dark blue starch is present
2. During photosynthesis light energy is absorbed by chlorophyll in the chloroplasts of the green parts of the plant. it is then used to convert carbon dioxide taken in by leaves and water taken in from the roots into glucose. oxygen is by product

Annotations:

• 3 limiting factors: -Lack of light -Cold (enzymes slower) -Little carbon dioxide

1. Lack of light. low temperature (enzymes denature). little carbon dioxide
   1. Experiments

      Annotations:

      • Independent variable: Concentration of Carbon Dioxide
      • Dependent Variable: Volume of Oxygen produced.
      • Control variables: Light, temperature, type of plant
      1. Independent Variable: Concentration of carbon dioxide
      2. Dependent variable: Volume of oxygen produced
      3. Control Variables: Light, Temperature and type of plant

Annotations:

• -Converted into insoluble starch for storage. -Respiration -Converted into lipids  and oils for storage. -Produce cellulose which strengthens cell walls. -Produce proteins.

1. Respiration: for growth and repair
2. Converting glucose into insoluble starch for storage
3. To produce fats or oils for storage
4. To produce fats, proteins or cellulose for use in the cells and cell walls
5. Plants an algae cells need a supply of mineral ions such as...
   1. Nitrate ions to produce protein
      1. Plants absorb Nitrate ions from the soil
      2. Algae absorbs nitrate ions from the water in which they live

Annotations:

• Plant growers can artificially control the environment to improve plant growth.
• To improve plant growth, the factors that need to be controlled are: -Light intensity -Temperature -Carbon dioxide levels

1. Plant growers can artificially control certain conditions in the environment such as temperature, light intensity and carbon dioxide levels to improve plant growth
   1. Polutunnels
      1. They are a long tunnel like green house. it controls conditions such as temperature and water. used to grow plants which need a hotter climate. this is very expencive needs a lot of man power and land
   2. Hydroponics
      1. These are big green houses with square water pools inside instead of soil to grow plants. They grow the plants on rafts in the pools. they control conditions such as temperature and water. This process grows plants all year round with less man power but costs lots of land and money

Annotations:

• The distribution of organisms is affected by environmental factors.
• -Temperature -Availability of nutrients -Amount of light -Availability of water -Availability of oxygen -Availability of carbon dioxide

1. The distribution of organisms is affected by environmental factors such as: Temperature, availability of nutrients, availability of water, availability of oxygen and carbon dioxide

Annotations:

• Quantitative data is used to describe how physical factors might be affecting the distribution of organisms in a habitat.
• There are two ways to obtain quantitative data: -Random quantitative sampling using a quadrat. -Sampling along a transect.

1. Sample size

   Annotations:

   • In a large field, enough random quadrats are needed so that the sample is representative of the entire field.
   1. In a large field, enough random quadrats are needed so that the sample is representative of the entire field
2. Quantitative data is used to describe how physical factors might be affecting the distribution of organisms in a habitat
   1. There two ways to obtain quantitative data
      1. Random sampling using a Quadrat

         Annotations:

         • -A square from which may be subdivided into a grid.  -Several quadrats are placed randomly and the thing being investigated is counted in each one. -It can be used to estimate the number of species or plant in a field.
         1. A quadrat is a square which can be subdivided into a grid. several locations are selected randomly (out of a hat). The quadrat is placed on the location and the thing you are investigating is counted in each location. This can be used to estimate the number of species or plant in a field
      2. Sampling along a Transect

         Annotations:

         • -This is not random. A line is marked between two points, and a random quadrat placed every 5 metres along the line. -Supplies a lot of information about:  --Habitat --Organisms in it.
         1. This is not random. A line is marked between two points, and a Quadrat is placed every 5 meters along the line. It supplies a lot of information about Habitat and the organisms in it

1. Proteins

   Annotations:

   • -Made up of long chains of amino acids. -Long chains are folded to produce specific shapes, which have a specific function.
   • They can be: -Structural components of tissues -Hormones -Antibodies -Catalysts
   1. made up of a long chain of amino acids which are folded into specific shapes which have particular functions

Annotations:

• -Reactions take place quicker if it is warmer. --At higher temperatures the molecules move around more quickly and so collide with each other more often, with more energy. (Learn this word for word)
• -Each enzyme works best at a particular pH value.

1. Denaturing

   Annotations:

   • If the temperature gets too hot, the active site CHANGE SHAPE, causing the enzyme to stop working.
   • If the pH is too acidic or too alkaline for the enzyme, the active site could change shape.
   1. If too hot or too acidic/alkaline the enzymes active shape can deform causing it to become denatured and inaffective
2. Reactions are faster when in certain conditions
   1. At a high temperature (makes molecules move around quicker increasing the amount of times they collide with each other which increases the amount of energy given off)
   2. Each enzyme works best at different PH's

Annotations:

• -These enzymes are produced in the glands and in the lining of the gut. -Enzymes pass out of the cells and come into contact with food. -Digestion involves the breakdown of large, insoluble molecules into smaller soluble ones.

1. Special enzymes
   1. Amylase

      Annotations:

      • Produced in the salivary glands, the pancreas and the small intestine.
      • Catalyses the digestion of starch into sugar in mouth and small intestine.
      • Work best when the conditions are slightly alkaline.
      1. Produced by the saliva gland and the pancreas. Catalyses the digestion of starch into sugars works best in alkaline conditions
   2. Protease

      Annotations:

      • Produced by the stomach, pancreas and small intestine.
      • Catalyses the breakdown of proteins into amino acids in the stomach and small intestine.
      • Work best when the conditions are acidic.
      1. Produced by the pancreas and stomach. Is a catalyst which breaks down protein into amino acids works best in acidic conditions
   3. Lipase

      Annotations:

      • Produced by the pancreas and small intestine.
      • Catalyses the breakdown of lipids to fatty acids and glycerol.
      • Work best when the conditions are slightly alkaline.
      1. Produced in the pancreas and small intestine breaks down fats and oils into fatty acids and glycerol works best in alkaline conditions
2. Bile

   Annotations:

   • -The liver produces bile. -Stored in the gall bladder before being released into the small intestine. -Bile neutralises the acid that was added to food in the stomach. -This provides alkaline conditions in which enzymes in the small intestine work most effectively.
   1. Is produced in the liver and stored in the gall bladder and released into the small intestine. The bile neutralises the acid that was added to the food in the stomach. It does this to make the solution alkaline so the enzymes in the small intestines can work better

1. Biological detergents

   Annotations:

   • -Contain proteases and lipases that digest food stains. -Work at lower temperatures than ordinary washing powders. -Saves energy and money spent on electricity.
   1. Contains protease and lipase which digest food stains. Work at lower temperatures than normal detergents as if too hot will become denatured and wont work as well. This saves energy and money spent on electricity
2. Baby foods

   Annotations:

   • Proteases are used to pre-digest proteins in some baby foods.
   1. Some baby foods have protease to help predigest food to help the baby eat and get amino acids
3. Fructose syrup

   Annotations:

   • -Isomerase is used to convert glucose syrup into fructose syrup.  -Fructose is MUCH SWEETER so less is needed in foods. -Foods are less fattening. 
   1. Isomerase is used to convert glucose syrup into fructose syrup. fructose is much sweeter so less is needed in foods making the foods less fattening
4. Foods

   Annotations:

   • Carbohydrases are used to convert starch into sugar syrup for use in foods.
   1. Carbohydrases used to convert starch in to sugar syrup which we use in foods
5. Industry

   Annotations:

   • -Used to bring about reactions at normal temperatures and pressures. -Traditional chemical processes require: --Expensive equipment. --A lot of energy (to produce high temperatures and pressures)
   1. Used to bring about reactions at normal temperatures and pressures. Traditional chemical processes require expensive equipment and a lot of energy for maintaining the high temperatures and pressures

1. Advantages

   Annotations:

   • -Enzymes in biological washing powders are very effective at removing stains. -Biological washing powders can be used at lower temperatures. -Used in medicine to diagnose, control or cure disease. -Industry, costs of equipment and energy can be reduced.
   1. Enzymes in biological washing powders are very efficient at removing stains
   2. Biological washing powders can be used at low temperatures
   3. Used in medicine to diagnose, control or cure disease
   4. In industry costs on equiptment and energy can be reduced
2. Disadvantages

   Annotations:

   • -Misuse of washing powders can cause allergic reactions on skin. -Enzymes may enter waterways via the sewage system. -Industrial enzymes are costly. -Enzymes denature at high temperatures needed to kill pathogens in the washing. -Fabrics such a wool are digested by proteases.
   1. Miss use of washing powders can lead to allergic reactions
   2. the enzymes can get into water ways via the sewage system
   3. industry enzymes are expencive
   4. enzymes denature at high temperature which makes it impossible to kill pathogens in washing
   5. Fabrics such as wool are digested by Protease

Annotations:

• -Takes place continually. -Chemical reactions take place in the mitochondria and are controlled by enzymes.

1. Glucose + Oxygen to Carbon dioxide + water (+energy)

   Annotations:

   • Glucose + oxygen  → Carbon dioxide + water [+ energy]
2. The energy produced is used to...

   Annotations:

   • Energy released used to: -Build larger molecules. -Enable muscle contraction. -Maintain a constant body temperature in colder surroundings. -Build sugars, nitrates and other nutrients into amino acids and then proteins in plants.
   1. Building larger molecules
   2. Enable muscles to contract
   3. Maintain body temperature
   4. build sugars, nitrates and other nutrients into amino acids and then proteins in plants
3. Experiment

   Annotations:

   • -Measure volume of carbon dioxide produced.
   1. Measure the volume of carbon dioxide produced
4. Creates more energy than anaerobic respiration

Annotations:

• -During exercise muscles need more energy. -More glucose and oxygen need to be transported to the muscles.

1. Heart rate increases which makes the blood vessels dilate to let the blood through to the muscles containing glucose and oxygen

   Annotations:

   • Increase and the blood vessels dilate to allow more blood containing oxygen and glucose to reach the muscles.
2. Breathing increasing allowing more oxygen in and carbon dioxide out

   Annotations:

   • Increase in breathing rate and depth of each breath to allow a greater uptake of oxygen and release of carbon dioxide in the lungs.
3. Glycogen is stored and is converted back into glucose during exercise

   Annotations:

   • Muscles store glucose at glycogen which can be converted back to glucose during exercise.

Annotations:

• When muscles work hard for a long time, they may have too little oxygen and become fatigued.
• Muscles use anaerobic respiration if they are short of oxygen.
• Anaerobic respiration doesn't break down glucose fully, therefore less energy is released from the glucose.

1. Energy to lactic acid (energy released)

   Annotations:

   • glucose → lactic acid (+ energy released)
2. Oxygen debt is how we deal with the build up of lactic acid it breaks it down

   Annotations:

   • In anaerobic respiration, lactic acid replaces carbon dioxide and water as the waste product.
   • When the exercise is complete, the lactic acid MUST be broken down.
   • The extra oxygen you need to oxidize the lactic acid into carbon dioxide and water is called oxygen debt.

Annotations:

• Necessary for the growth of an organism, or for the repair of damaged tissues.

1. Mitosis: two identical cells produced from original cell

   Annotations:

   • Two identical cells being produced from the original cell. Mitosis = Making Identical Two
   • Two identical cells being produced from the original cell. 46 chromosomes (2 sets) Mitosis = Making Identical Two
   1. Chromosomes

      Annotations:

      • Found in pairs and contain genes (alleles) which must be passed onto each new cell.
      1. Found in pairs contain genes (alleles) which must be passed on to each new cell
   2. Process

      Annotations:

      • -Normal body cell has 46 chromosomes (23 pairs). -Copies of these pairs are made. -Then the cell divides once to form two genetically identical body cells.
      1. Normal body cell as 46 chromosomes (23 pairs)
         1. These pairs are copied
            1. The cell divides forming two identicle cells
   3. Asexual cells

      Annotations:

      • Asexual reproduction cells are produced by mitosis from the parent cell. They contain the SAME alleles as the parents.
      1. Produced by mitosis from parent cell contain same alleles as parent
2. Meiosis: cells in reproductive organs divide to form gametes 23 chromosome is one set. meiosis makes eggs

   Annotations:

   • -Cells in reproductive organs divide by meiosis to form gametes.  -23 chromosomes (one set) -Meiosis = Making Eggs
   1. Process

      Annotations:

      • -Before division, a copy of each chromosome is made. -The cell now divides twice to form four gametes. -Each gamete has a single set of chromosomes with a different combination of genes. 
      1. A copy of each chromosome is made
         1. The cell divides twice into 4 gametes
            1. each gamete has a single set of chromosomes with a different combination of genes
   2. Sexual reproduction

      Annotations:

      • -Results in variation as the gametes from each parent fuse. -Half genetic information from mother, half from father. -In fertilization, a single body cell with new pairs of chromosomes form. -Individual develops through mitosis. 
      1. Results in variation as the gametes from both parents fuse. half from each
      2. in fertilization a single body cell with new pairs of chromosomes form. this develops by mitosis to form another individual
3. Differentiation

   Annotations:

   • Most animal cells differentiate early in development and cell division is mainly for: -Repair -Replacement
   • Plant cells can differentiate throughout the life of the plant as it continues to grow.
   1. Most animal cells differentiate early in development cell division is mainly for repair/ replacement

Annotations:

• -Unspecialised. -Found in human embryo and bone marrow. -Differentiate into different types of body cell. -Adult bone marrow stem cells - can differentiate into blood cells.-Hoped that stem cells could be used to cure diseases.

1. Embryos: embryonic stem cells can be used in medical research and treatments

   Annotations:

   • Embryonic stem cells can be used in medical research and treatments.
   • Found: -Spare embryos from IVF. -Created from adult cells. -Taken from the umbilical cord of newborn babies.
   1. Issues
      1. Economical

         Annotations:

         • Very expensive to carry out research using embryonic cells.
         1. Very expencive
      2. Ethical

         Annotations:

         • -The research is experimental. -Embryos have potential to become a baby and are destroyed. -Embryo cannot give permission.
         1. Its experimental
         2. Embryos are potential babies which are destroyed (murder?)
         3. Embryos don't have a say
   2. Embryo screening: is able to find out if the embryo has any disorders

      Annotations:

      • Involves tests to diagnose disorders before the baby is born.
      1. Results

         Annotations:

         • -Sometimes parents decide to terminate the pregnancy. -Others decide it isn't ethical and keep the baby.
         • In IVF, only healthy embryos are implanted into the mother. Embryos carring FAULTY genes are destroyed, which isn't ethical.
         1. Parents decide to terminate the pregnancy
         2. Some decide it is not ethical and keep child

1. Sex chromosomes
   1. Male provides a X and Y chromosome

      Annotations:

      • An X and a Y chromosome (XY)
   2. Female provide two X chromosomes (XX)

      Annotations:

      • Two X chromosomes (XX)
2. Alleles: genes that control the same characteristics

   Annotations:

   • Genes controlling the same characteristic.
   1. Dominent

      Annotations:

      • 'Masks' the effect of another allele.
      1. This will always show even if there is only one
   2. Recessive

      Annotations:

      • The dominant allele 'masks' this allele, so it has no effect.
      1. The characteristic controlled by a dormant allele develops if the allele is present in both pairs of chromosomes
3. Genetic disorders: if recessive it needs two alleles to have the disorder if dominent only needs one

   Annotations:

   • If an allele is recessive, the person must inherit two recessive alleles to have the disorder.
   • If the allele is dominant, the person has to inherit only one dominant allele to have the disorder.
   1. Polydactyly

      Annotations:

      • -Caused by a dominant allele. -Where a baby is born with extra fingers or toes.
      1. Caused by dominent allele where a babby is born with extra fingers/toes
   2. Cystic fibrosis

      Annotations:

      • -Caused by a recessive allele. -Affects cell membranes and causes the production of thick sticky mucus. 
      1. Caused by recessive allele affects cell membrane and causes the production of mucus
   3. Carriers: people who carry recessive alleles

      Annotations:

      • People who carry a recessive allele.
4. Punnet squares: can be used to predict the chances of inheriting characteristics

   Annotations:

   • Used to predict the chances of inheriting a disorder.
   1. Genotype: the genetic make up, which alleles does the individual inherit (DD, Dd, dd)

      Annotations:

      • The genetic make-up, which alleles does the individual inherit.  (DD, Dd, dd)
   2. Homozygous: both alleles are the same (dominent DD) (recessive dd)

      Annotations:

      • Both alleles are the same DD (homozygous dominant) or dd (homozygous recessive).
   3. Heterozygous: two alleles are different (Dd)

      Annotations:

      • The two alleles are different, Dd.

1. Genes are strands of DNA which are found on chromosomes which control characteristics

   Annotations:

   • -Found on chromosomes. -Control our characteristics. -Short section of DNA.
   1. Genetic code: genes are coded for particular combinations of amino acids which make specific proteins

      Annotations:

      • Each genes codes for a particular combination of amino acids which make a specific protein.
2. DNA Fingerprint: a unique DNA pattern that can be used to identify you

   Annotations:

   • Unique DNA pattern which can be used to identify people.

Annotations:

• -Believed that the Earth is 4500 million years old and that life began about 3500 million years ago. -There is DEBATE as to whether first live developed due to conditions on Earth, or whether simple life forms arrived from another planet.

1. Fossils

   Annotations:

   • -Fossils are remains of organisms from many years ago which are found in rocks. -We can learn from fossils how different organisms have changed as life developed on Earth.
   • -The fossil record is INCOMPLETE.
   1. How they are formed

      Annotations:

      • -From hard parts of animals that do not decay easily (teeth, claws) -From parts of organisms that have not decayed because some of the conditions for decay are absent (ice preservation). -When parts of the organism are replaced by other materials, such as minerals, as they decay. -As preserved traces of organisms (footprints, burrows).
      1. From hard part of animals teeth bones which don't decay easily.
      2. can form when conditions for decay are not present
      3. when parts of the body are replaced by minerals as they decay
      4. Traces such as foootprints
   2. traces can be destroyed by natural desasters

      Annotations:

      • Traces which were left are likely to have been destroyed by geological activity such as earthquakes.
   3. Soft-bodied organisms cant leave fossils

      Annotations:

      • Soft-bodied organisms didn't leave fossils.
   4. Fossil evidence

      Annotations:

      • -Shows that there have been mass extinctions on a global scale. -Many of the species died out over a period of several million years - a short time.
      • -The habitat the species live in may be destroyed by catastrophic events such as a major volcanic eruption. -The environment can change dramatically following a collision between a giant asteroid and Earth.
      1. Extinction : when a whole species dies out

         Annotations:

         • A species which once existed has completely died out. 
         1. Factors

            Annotations:

            • -A new disease may kill all members of a species. -Change in environment. -New diseases may be introduced. -A new predator may evolve or be introduced to an area that kills and eats all of a species. -A new competitor - original species may be left with little or nothing to eat. -A single catastrophic event may occur which destroys the habitat. -Natural changes in species occur over time.
            1. A disease may wipe out a species/ a new disease introduced
            2. Changes in the environment
            3. A predator may be introduced or adapt which causes it to wipe out all species
            4. New competitors may reduce food available killing other species
            5. A catastrophic event causes mass extinction
            6. Natural changes in species
      2. Shows mass extinction/species deing out, how organisms arise and how they are formed
      3. fossil record is incomplete as fossils are destroyed by the core of the earth

Annotations:

• The biggest influences on a species survival are changes in the environment.

1. Climate change can cause extinction for animals adapted to hot climate via a ice age as there could be no food or too cold to breed

   Annotations:

   • -A species which is very well adapted to a hot climate may become extinct in an Ice Age. -There could be insufficient food or it is too cold to breed.
   • -Climate change may: --Make it too cold or hot. --Make it too wet or dry. --Reduce a species food supply.
2. The dinosaurs

   Annotations:

   • No one knows why they have become extinct. Some ideas are: -The collision of a giant asteroid caused huge fires, earthquakes, landslides and tsunamis. The dust which rose blocked out the sun, lowering temperatures and causing darkness. Plants could not grow. -The extinction was a slower process due to sea ice melting and cooling the sea temperature by 9 degrees, therefore there was less plankton - less food available. 
   1. went extinct via giant asteroid colllision creating thousands of natural disasters throwing so much dust into the air it blocked out the sun killing plants and their prediators. it also dropped see temperature by 9 degrees killing lots of fish

Annotations:

• New species can arise form existing species if a group becomes isolated from the rest.

1. Isolation leads to genetic variation leads to alleles selected (survival of the fittest) leads to interbreeding no longer being possible creating a new species (speciation)
   1. Genetic variation: different variations of species protects against a epidemic

      Annotations:

      • Each population has a wide range of alleles that control their characteristics.
      1. Natural selection:The process whereby organisms better adapt to their environment tend to survive and produce more offspring. survival of the fittest

         Annotations:

         • -Occurs in both populations. -The alleles that control the characteristics which help the organism to survive are selected. -The organisms with these alleles will survive and breed.
         1. Evolution: The process in which different types of living organisms are to believed to have developed

            Annotations:

            • If the environment, competitors, food supply and predators are different for each population, they will evolve differently. 
            1. Interbreeding: breeding which takes place between two similar but different species (wolves and dogs can interbreed)

               Annotations:

               • SPECIATION has occurred when the two populations can no longer successfully interbreed.
   2. Isolation

      Annotations:

      • New species can occur following separation of two populations, as in geographical isolation. 
      1. Geographical isolation: A species are separated by..

         Annotations:

         • -Could occur if an island separates from the mainland or if a new river separates two areas. -Mountain ranges and old craters can isolate organisms. 
         1. When a island is separated from mainland
         2. Mountain ranges
         3. Rivers