Biology YEAR 9 EOY

Variation

The differences between individuals due to genes, the environment or a combination of both.

Intraspecfic variaition

Differences between organisms of the same species

Interspecific variation

Differences between organism from different speices

Combined Causes of Variation

Genetic - Determined by genetic code

Environmental - Determined by factors other than genes

Genotype

An organism's genetic composition. (DNA Sequence)

Phenotype

An organism's observable characteristics.

Mutation

A random change in DNA which may result in genetic variation.

Evolution

Evolution is the change in the heritable characteristics of biological populations over successive generations.

Natural Selection Process

1 - Random Mutation Occurs

2 - This mutation makes the organism better suited to the environment.

3 - Which increases their chance of survival

4 - Giving them more opportunities to reproduce

5 - And then pass on their successive trait to their offspring.

6 - Overtime the characteristic becomes so common that the species evolve

Selective Breeding

The process by which humans artificially select organisms with desirable characteristics and breed them to produce offspring with desirable phenotypes.

Selective Breeding Process

1 - Organisms with desired traits are selected to breed

2 - Their offspring are then observed for the desirable characteristics

3 - The best offspring are then selected to breed again to make more offspring with desirable traits.

4 - This will continue for several generations and eventually the offspring will have the characteristic.

Disadvantages of Selective Breeding

- Inbreeding

- Less Genetic Variation

-Slow Process

- organisms being vulnerable to new diseases (there is less chance of resistant alleles being present in the reduced gene pool)

Darwin's Theory of Evolution

natural selection

Lamarks Theory of Evolution

Individual organisms changed as they adapted to their environment and passed on these changes to their offspring. (Giraffe eg)

Why people didn't accept Darwin's ideas

- Religious Reasons

- Lack of Evidence

- DNA wasn't discovered

Lamark's Theory is incorrect due to

If a humans got tattoos then his offspring would not be born with tattoos.

Speciation

The formation of new species in the course of evolution, often due to the evolution of two isolated populations. (Darwins Finches)

Process of Speciation

1 - Species is separated due to physical barriers.

2 - Condition of either side of may be different

3 - Different characteristic would be more common due to natural selection

4 - Eventually different population have changed so much that they will not produce fertile offspring.

5 - The two groups have become separate species.

Antibiotical resistance

When bacteria change to resist antibiotics that used to effectively treat them.

Process of Antibiotical Resistance

1 - A person is prescribed antibiotics(maybe for wrong reasons)

2 - The person takes antibiotics until they feel better

3 - The persons stops taking antibiotics before the course if finished

4 - Only the resistant bacteria are left alive.

5 - These resistant bacteria are able to clone themselves until the whole population is resistant.

6 - Antibiotics are no longer effective for that bacteria.

Fossils

The remains of dead organisms found in rocks which are millions of years old.

3 Ways Fossils Form

- Gradual replacement by minerals,

- casts and impressions

- preservation in places where no decay happens

Extinction

The death of all members of a species.

Incomplete Fossil Records Reason

- Undiscovered Fossils

- Some animals were not fossilised

- Fossils may have been destroyed by geological activity

- First organisms were soft bodies

Fossilisation Process

1. Organisms Dies

2.It gets buried under layers of sediment like rocks/mud.

3.This prevents exposure to oxygen.

4.The organisms soft parts decay

5.Minerals replace the hard parts of an organism turning it into rock (permineralisation)

Ways Animals Can go Extinct

- Predators

- Hunting/Poaching

- Disease/Infections

- Climate change and natural disasters

classification system

Kingdom, Phylum, Class, Order, Family, Genus, Species

Binomial Naming System

Genus , species

Species

A group of similar organisms that can breed and produce fertile offspring.

Catalyst

Substance that increases the speed of a chemical reaction without being used up in the process.

Enzymes

Biological catalysts that increase the rate of reactions in living organisms.Without being changes or used up in the process.

Carbohydrate

- Gives us the fuel to respire and carry out biological processes

- Simple sugars one unit of sugar(glucose)

- complex sugars many units of sugar (cellulose)

- Bread,Pasta,Rice

Proteins

- Uses to build up cells and tissues

- Structural (keratin) and Functional (Enzymes)

- Made from long chains of amino acids

- Meat,Fish,Beans

Lipids

-Efficient energy store (Fats and Oils)

- Use for insulation and protection

- Glycerol back bone with 3 fatty acids (which change)

- Dairy,Fish,Nuts

Enzyme

A biological catalyst which are made up of long chains of amino acids.

Lock and Key Theory

The enzyme is the lock and the substrate it the key. The enzyme is complementary to the active site of the enzyme to form the enzyme/substrate complex. The enzyme break (or builds) the substrate down into products.The enzymes is not used up during the reaction.

Induced Fit Model

Similar theory to lock and key however talks about how the enzymes active site slightly changes shape to fit the substrate and so is "complementary".

Factors that affect enzyme activity

- Temperature

- PH

Effect of Temp/PH on Enzymes

Low (less kinetic energy) → Optimum (perfect) → Denaturing (decreases reactions rate until it denatures)

Biomolecules

Molecules found in living organisms and are produced in cells.

Nutrients

Substances need for growth repair and metabolism.

Enzymes that break down carbohydrates

(Amylase) An enzyme produced in the salivary glands and pancreas + small intestine that breaks carbohydrates down into simple sugars.

Enzymes that break down protein

An enzyme produced in the stomach (pepsin) and pancreas +small intestine that breaks proteins down into amino acids.

Enzymes that break down lipids

An enzyme that is produced in the pancreas+small intestine that breaks lipids down into fatty acids and glycerol.

Cells

Basic building blocks of life.

Active transport

The movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient) with the use of energy from respiration.

Adult stem cell

A type of stem cell that can form many types of cells.

Cell differentiation

The process where a cell becomes specialised to its function.

Cell membrane

A partially permeable barrier that surrounds the cell.

Ribosomes

Organelle responsible for making protein

Cellulose Cell wall

An outer layer made of cellulose that strengthens plant cells.

Chloroplast

An organelle which is the site of photosynthesis.

Chromosomes

DNA structures that are found in the nucleus which are made up of genes.

Concentration gradient

The difference in concentration between two areas.

Diffusion

The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.

Factors that Affect Diffusion

Concentration Gradient/Temperature/Surface Area/Distance across a membrane (if applicable)

Stem cell

Unspecialized cell that can develop into a specialized cell through the process of differentiation

Eukaryotic cell

A type of cell found in plants and animals that contains a nucleus.

Magnification

How much bigger an image appears compared to the original object.

Meristem cells

A type of stem cell that can differentiate into any type of plant cell.

Mitochondria

An organelle which is the site of aerobic respiration. Releases energy for the cell to use.

Mitosis

A type of cell division which produces two genetically identical daughter cells from one parent cell.

Nucleus

An organelle found in most eukaryotic cells that contains the genetic material of the cell and controls the activities of the cell.

Organelle

A specialised structure found inside a cell.

Osmosis

The diffusion of water from a dilute (high concentration of water) solution to a concentrated solution (low concentration) through a partially permeable membrane.

Water Concentration

The amount of water compared to solute which determines the concentration.

Plasmid

Loops of DNA found in the cytoplasm of prokaryotic cells.

Prokaryotic cell

A type of cell found in bacteria that does not contain a nucleus.

Resolution

How detailed the image is

Specialised cells

Cells that are adapted to carry out a particular function

Embryonic Stem cell

An undifferentiated cell, taken from an embryo that has potential to give any specialised cell with differentiation.

Vacuole (permanent in plants)

An organelle that stores cell sap.

Image size

how large the object appears when you view it through the microscope

Object size

the real size of the object

Base

Bottom of Microscope

Arm

Used to support the microscope when carried

Light Source

Provides light to the micrscope.

Stage

Supports the slide being viewed

Objective Lenses

Magnification ranges from 10x to 40x

Eye Piece Lens

Contains a lens that magnifies 10x

Coarse Focusing Knob

Moves the stage of the microscope up and down to focus the image.

Fine focusing Knob

Slightly moves the stage up and down for focusing

Image

The image shown when we look down the microscope.

Object

The real object or sample that you are looking at.

Magnification Formula

Magnification = Image Size/Object Size

Light Microscope

- Easy to use

- Relatively Cheap

- Resolution limited to 0.2um (wavelength of light)

Electron Microscope

- Hard to use

- Expensive

- Resolution of 0.1nm (wavelength of electrons)

Cell Cycle

Life cycle of a cell that starts with a cell being produced and ends with a cell dividing to make two identical daughter cells

Stages of Cell Cycle

1.In a cell that is not dividing DNA is spread out in long strings

2.Before dividing the cell has to grow and increase the amount of sub-cellular structures

3. It then duplicates its DNA so there will be one copy of each chromosome for each new cell. It will for X shaped chromosomes and each arm are exact duplicates.

4.The chromosomes line up at the centre of the cell and cell fibres pull them apart the two arms of each chromosome go to opposite ends of the cell

5. Membranes from around each set of chromosome these become the nuclei of the two new cells.

6. Lastly the cytoplasm and cell membrane divide to produce two daughter cells.

Growth Phase (Steps 1-3)

DNA and organelle duplication (mitochondria and ribosomes)

Cytokenisis (Step 6)

The cell divides into two

Mitosis PMAT (Steps 4-5)

Prophase- Chromosones Condense

Metaphase - Chromosones line up in the middle and spindle fibres attach to either side.

Anaphase - Spindle Fibres pull each half of the chromosones apart to form chromatids.

Telophase - Cell membrane starts to form and two nuclei are produced.

Osmosis Practical Process

1.Cut potato into identical cylinders and measure their masses. No skin left.

2. Get some beakers with different sugar solution in them. One is pure water and another is concentrated sugar solution (different concentrations)

3. Place on potato cylinder in each beaker .Leave them in for some time

4. Take the cylinders out dry them with paper towel and measure mass

5. If cylinders have draw in water they have increased in mass. If water was drawn out they decrease in mass.

DV - Cylinder mass

IV - Concentration of the sugar solution

CV - temp,time,type of sugar

Microscopy Practical Process (Preparing Slide)

Prepare Slide

1. Add a drop of water to middle of clean slide

2. Cut an onion and separate it out into layers.Use tweezers to peel of epidermal tissue .

3.Place tissue into the water on the slide with tweezers

4. Add a drop of iodine solution it is a stain.

5.Place a cover slip on top. Try not to get air bubbles under the slip.

Enzymes Practical Process

1. Heat a water bath to 35°C and add 2 cm³ of each buffered solution into separate test tubes, labeling them with their pH.

2. Label 5 test tubes 'Starch' and add 4 cm³ of starch solution to each. Place a thermometer in one tube to monitor the temperature.

3. Add 10 cm³ of amylase solution into a labeled test tube and place all the test tubes in the water bath.

4. Allow the solutions to reach 35°C. While waiting, add one drop of iodine solution to each depression of a spotting tile and add a drop of starch to the first depression as a 'zero time' mixture for comparison.

5. Once the solutions reach 35°C, take one starch tube from the water bath and add 2 cm³ of the first pH-buffered solution, stirring with a glass rod.

6. Add 2 cm³ of amylase solution, start the stopwatch, and stir the mixture.

7. After 10 seconds, remove a drop of the mixture with a glass rod and place it on the second depression of the spotting tile. Rinse the glass rod with water.

8.Every 10 seconds, remove a drop of the mixture and place it on the next iodine depression, rinsing the rod after each drop.

9.Continue until the iodine no longer changes color and record the results in a table.

What happens to chromosomes before cell replication?

Chromosomes are usually uncoiled, when a cell prepares to divide they fold up into 'worm-like' structures that we recognise

Why do our bodies need a new supply of cells?

Organisms need a new supply of cells to grow (more cells )develop (new cells for new tissues etc.)and repair (cells to replace damaged/dead ones)

Two Features of Stem cells

1. Can divide by mitosis to form new cells

2.They can differentiate into specialised cells

Steps of Stem cells in humans

1.When a sperm cell fertilises an egg cell they form a single cell called a zygote.

2.This cell then divides by mitosis to form a ball of cells which we call an embryo.

3.The cells in this embryo are known as embryonic stem cells and can differentiate into any type of cell.

4. When humans become adults they can find stem cells in certain places they can divide by mitosis but only specialise into some cells.

Meristem cells (Location)

- Tips of roots and shoots (growing region of the plant)

- Fully Undifferentiated can differentiate into anything