2.75 Urine

- The brain influences the functioning of the two kidneys
- The two kidneys are filtering our blood
- The molecules which are removed and come down the ureter collect in the bladder
- This forms urine
- Urine contains salts, water and urea
- Salt and water affect the composition of tissue fluid - osmoregulation
- Removal of urea is a part of the process of the excretion of metabolic waste
- The composition of urine varies and depends upon the conditions in which a person is operating

2.74 ADH.

- ADH (Anti-Diuretic Hormone)
- It is produced in a region of the brian known as the Hypothalamus. It flows through the blood stream and its target is the kidney
- The effect of ADH is to control and alter the composition of water which is in blood
- ADH has the ability to make the blood more or less concentrated
- It is important to have the tissue fluid isotonic to the cytoplasm of the cell
- ADH targets the collecting duct
- It allows more water to come out of the collecting duct
- The consequence of ADH secretion is that the urine coming from the nephron would be more concentrated and would have a lower volume

2.73 Glucose reabsorption

- "Selected reabsorption" means that glucose will go from the Glomerular filtrate back into the blood
- Water is moved back into the blood at the collecting duct
- Coming out of at the end of the nephron is urine, normally, it does not contain glucose
- Diabetes is when you test your urine and receive a positive test = there is glucose in your urine.
- In the PCT (proximal convoluted tubule) glucose is removed and is taken back into blood

2.72 Water re-absorption

- The dissolved contents of the blood are forced into the Bowman's Capusle and is known as the Glomerular filtrate (it contains glucose, water, salts and urea).
- When the filtration occurs, it will filter out too much water
- As the filtrate reaches the collecting duct and passes through it, water is removed from the filtrate and the water goes back into the blood vessels.
- The water has been selected and reabsorbed into the blood.
- Therefore, there is the word "selective reabsorption"
- "Selective reabsorption" occurs in the collecting duct.

2.71 Ultrafiltration

- The first process occurs at the Bowman's capsule - the filtration process begins.
- Blood arrives in the kidney in the afferent arteriole, a wide vessel (coming in - high pressure).
- The blood vessel coming out has a smaller diameter than the one coming in. This means that it develops a high pressure. The blood pressure increases in the glomerulus.
- The high pressure forces the liquid within blood, plasma (contains water, salts, amino acids, glucose and urea), out of the blood vessel and into the space = inside of the Bowman's capsule.
- When the plasma is forced into the Bowman's capsule, plasma --> "glomerular filtrate"

2.70 Nephron Structure

First Diagram:
- Nephron = The functional unit of the kidney, the part that does the filtration and controlling of the composition of blood
- Pelvic region - where the urine collects and drains down the Ureter
- There are different colours because the kidney is made up of millions of tubular structure
- The tube starts on the edge of the medulla and moves directly upwards and out into the cortex. It winds and then dips down into the medulla again and then up, there is another short twisted section and then a dead end.
- The dead end structure is known as the Bowman's capsule.

Second diagram:
- The tube is made up of twisted sections. Convoluted tubules.
- The tube at the bottom is known as the collecting duct.
- The dip is known as "the loop of Henle"
- The first twisted section = proximal (PCT)
- The second twisted section = distal (DCT)
- It is the arrangement of this nephron structure which gives the different coloured region in the kidney.

2.69 Urinary System

1. 2 Kidneys.
- Each have their own blood supply
- Carry out the process of excretion, filtration and osmoregulation
- Each kidney there is tube that leads to the bladder = Ureter

2. Ureter
- Carries urine from the kidney to the bladder

3. Bladder
- One bladder for both ureters

4. Urethra
- Urine is conducted to the outside of the body to be excreted
- Either travels down through vagina or penis.

2.68b Osmoregulation

Role of the kidney in the process of osmoregulation:
- Osmo = osmosis, Regulation = control
- The tissue fluid surrounding the cells must be isotonic (amount of water going into and out of the cells are equal and the cells will remain the same size and shape and maintain their function) with the cytoplasm of the cells.
- The danger to the tissue is that blood circulating into the tissue would be concentrated causing a "hypertonic" tissue fluid or may be dilute causing a "hypotonic" tissue fluid.
- Need to keep the tissue fluid isotonic
- Achieved by controlling the composition of blood. Blood forms the tissue fluid.
- The kidney controls the composition of our blood.
- The kidney removes excess water and salts from the blood which circulates through our kidney and excreted.
- By controlling the content of water and salts in the blood, the tissue fluid surrounding the cells will be isotonic with the cytoplasm of the cells.

2.68a Excretion

The role of the kidney:
- Excretion of Urea ( contains nitrogen - toxic to the body and cannot be stored)
- The original form of nitrogen are amino acids (used for growth but too much must be removed)
- Blood circulates into the liver and breaks down and converted into Urea.
- It re-enters the blood stream and circulates to both kidneys.
- The kidneys will filter the urea from the blood and will be added to water to form urine.
- The urine drains down the uterus to collect in the bladder. (in form of urine)
- The filtered blood returns to the circulation in the veins with the toxic amino acids and urea removed.

2.67b Human Organs of Excretion

1. Lungs:
- Carbon dioxide is excreted from respiration

2. Kidneys:
- Responsible for the excretion of excess water, urea (nitrogen waste from amino acids) and salts

3. Skin:
- Excrete water (by sweat) , salts (by sweat) and urea (only a little bit of urea)

2.67a Excretion in plants

1. Process of photosynthesis:
- involves the leaf absorbing light energy
- in the process it combines carbon dioxide with water to form glucose and gives off oxygen.
- CO2 + H20 ---> C6H12O6 + O2 (<-- waste molecule = example of excretion - release of metabolic waste)

2. Respiration:
- Glucose is required and oxygen (aerobic respiration)
- The molecules is broken down by enzymes to create ATP and carbon dioxide and water.
- C6H12O6 + O2 ---> ATP + CO2 (<--- waste molecule = excretion) + H20

3.34 Causes of Mutation

- What causes mutation?
1. Radiation: x-rays, UV-B rays (mutations that can cause diseases such as skin cancer)
2. Chemicals: Tars in tobacco (cancerous conditions).
- Chemicals which cause mutations are called mutagens.
- Chemicals which cause mutation known as mutagens which also cause cancer are called carcinogen.

3.33 Antibiotic Resistance

- As antibiotics are used across time, the resistant form of Staphlococcus aureus (MRSA) increasingly survives and more common.

- In time, it becomes a serious problem within hospitals and the treatment of people with wounds because the antibiotic no longer works.

3.32 Types of Mutation

- Gene ---(mutation)---> New alleles.
- The alleles are responsible for the phenotype.
- Impact could be:
1. Beneficial [e.g. improve the efficiency of an enzyme]
2.Neutral ( no effect ) [at the point in time has no effect although the neutrality may not last forever and in time, with environmental change, may become harmful or beneficial]
3. Harmful [e.g. the mutation leads to production of an enzyme with doesn't work - non-functional]

3.31 Evolution

- Evolution:
1. change in the form of organisms
2. Chang in the frequency (how many) of alleles
- Natural Selection is the mechanism of evolution and was first proposed by Charles Darwin.
- Example: skin infections by the bacteria staphlococcus aureus.
- Methecilline is a type of antibiotic that kills staphlococcus aureus. The staphlococcus areus that can be killed by this antibiotic are described as the susceptible forms.
- What occurs: a random mutation to the genome which allowed it to develop the characteristic of breaking down methecilline. It therefore, no longer killed by the antibiotic and are described as the resistant form.
- 2 form of the bacteria = evolution.
- When antibiotics are applied to the MSSA population, it decreased
- because MRSA is resistance, they becoming increasingly common = evolution
Features:
1. Random mutation - MRSA form
2. Non-random selection - Antibiotic selecting the MRSA to survive and MSSA to be selected and killed.
- The two components are classic features of Natural Selection.
- Natural selection is a process and not a thing.

3.30 Mutation

- DNA, the base sequence (ACT) constitutes the Gene and the form of the Gene is called the Allele
- Certain processes can result in the change of the base sequence (into AAT).
- This change creates a new version of the allele
- It is possible that it will result into the production of an entirely different protein and have an entirely different effect on the phenotype.
- Different alleles (dominant and recessive) exist because of the process mutation = changes the base sequence of the gene.

3.29 Species Variation

- Variation = differences that we can see in the phenotype of individuals. Possible to count/measure these differences in graphic form.
- Individual: Phenotype = Gene + Environment
- Variation: V(population) = V(genorype) + V(environment)
1. Variation in population entirely due to Variation in Genotypes. (e.g. Blood groups) - Discontinuous
2. Variation in population/species due to Variation in Genotype and are modified by the environment to form the distribution curve (e.g. height of individuals) - Continuous
3. Variation in population entirely due to the environmental variation. (e.g. Home language). Cannot be inherited.

3.21b Genetic Probabilities

Parent Phenotype:
Red petal x Red petal

Parent Genotype:
Rr x Rr (both parents are heterozygotes)

Meiosis:
The alleles need to be separated one into each type of gamete.
1/2R, 1/2r (50 percent chance that the pollen grain will carry each of these)

Random Fertilization

Genotypes of the offspring:
RR : 2 Rr : rr

Phenotype ratio:
Red : Red : White, 1 : 2 : 1
- There is a 3 : 1 ratio (Red : White)(75% : 25%)(3/4 : 1/4)

These are probabilities, it depends which pollen grain fertilizes which ovule.

3.21a Genetic Probabilities

Parents:
Red Petals x White Petals

Genotype:
RR x rr (R>r, Red > White)

The next stage involves meiosis. The gamete will contain only one of the two alleles but it is an equal chance. 1/2 R or 1/2R x 1/2r x /2r

Random fertilization:
Drawing a table to illustrate the possible fertilizations that can occur between the pollen grains and the ovule.

Genotype of the offspring: ALL Rr,

Phenotype of offspring: all Red

Probability of Red x White = 100% Red Petaled flower.

3.20b Pedigree 2

3.20a Pedigree Diagrams

3.18c Codominance

Blue petal plant(B- has a genotype of BB) + White petal plant(W- has a genotype of WW) --- cross ---> Orange petal plant (unusual third phenotype which is orange)

Work out the genotype of the third phenotype:
When the blue petal plant reproduces with the white petal plant, it contributes one allele each. The heterozygote must be BW but generates a third, different distinct phenotype = CO-DOMINANCE

Both alleles B and W contribute to the phenotype and gives off the orange colour in this case.

3.19b F1 x F1 Cross

3.19b Describe patterns of monohybrid inheritance using a genetic diagram

3.19a P1 x P1 Cross

3.19a Describe patterns of monohybrid inheritance using a genetic diagram

3.18b Genotypes

3.18b Recall the meaning of the terms: dominant, recessive, homozygous, heterozygous, phenotype, genotype and codominance

3.18a Phenotypes

3.18a Recall the meaning of the terms: dominant, recessive, homozygous, heterozygous, phenotype, genotype and codominance

3.2 Fertilisation

3.9b Female Reproductive System

3.9a Male Reproductive System

3.12 Amniotic Fluid

3.11 Placenta

3.24c Mitosis 3

- Interphase - unable to see the process of DNA replication
- The first sign that the cell is entering mitosis and DNA division is when we see the break down of the nucleus, this phase is known as the "Prophase", the membranes brake down and the chromosomes become visible. They are visible as a pair of chromatids.
- Once the nucleus is gone, inside the cell, a network of protein molecules known as the "Spindle" and the "spindle fibres" that extend from one pole of the cell to the other. This is the "Late prophase" - The pair of chromatids will move towards the spindle and join onto one of the spindle fibres at the centrameere
- "Metaphase" - the pair of chromatids are attached to the spindle fibre by the centrameere. Characteristics = the chromosomes are in the middle, arranged across the equator of the cell
- The "Anaphase" - the spindle fibre shortens, pulling one chromatid in one direction and another in the other direction. The pair of chromatids are move apart and move to the poles of the cell. The pair of chromatids are separated.
- "Telophase" - The nucleus begins to reform around the chromosomes at either end of the cell. This will be the new nucleus of the new cell. See the formation of two nuclei, two sets of chromosomes at opposite ends of the cell
- "Cytokinesis" - The cells splits in two - NOT part of mitosis. The cell begins to move in-words in the middle, dividing the cytoplasm in half and the membrane will fuse across the equator to form the two cells. They each contain a chromosome. Both cells have chromosomes that are the same as the parental cell.
- In humans, we don't see one pair separating, but 23 pairs separating at the same time

3.24b Mitosis 2

- Copying the chromosomes is a process called "DNA replication"
- In the process, the chromosome undergoes a copying process to form an identical copy of itself with all the same genes and all the same alleles
- The copies are held together by a structure around the centre region called the "centromere"
- While the chromosomes are in a copied pair held together by a centromere, we refer to them as a "pair of chromatids"
- The process takes place inside the nucleus while the nucleus is still intact. We can't see this process. This is known as the "interphase" of the cell cycle.

3.24a Mitosis 1

- Mitosis - a form of cell division which results in growth. The growth occurs by an increase in the number of cells
- Begin with a normal cell with its nucleus. The number of chromosomes in the nucleus is known as the "Diploid" number = 2n,
- For humans, 2n = 46
- Cats, 2n = 38
- In the process, the cell will divide into 2 cells, each with a nucleus. Each of the nucleus has a Diploid nucleus. These cells are identical (or daughter cells).
- Identical because:
1) Same number of chromosomes
2) Same set of chromosomes (meaning, if we choose one chromosome from one of the cells, another version of the same chromosome will be found in the other cell)
- The questions which rise from this process:
1) "How are the copies of chromosomes made?"
2) "How do they separate into the two cells?"

3.16 DNA and Genetic Information

- Chromosomes are likely to contain thousands of genes
- When the gene loci is expanded, you will find a double helix (because there are two helixes) and they appear to be parallel
- Once the two strands of the helix is expanded you will see what is holding the two helixes together
- The sections on the outside are known as the "sugar - phosphate backbone"and in the centre there are a group of molecules called "Bases", the four different types of bases are: Adenine, thymine, eytosine and guanine
- In the molecules, these bases are holding together the two helixes. They are held together by the pairing between: Adenine and thymine on one side and cytosine and guanine. These are known as the "base pairs". They are gluing together one side of the DNA double helix with the other.
- The order of the bases: A-C-T-G-A-A-C-C-A-G, it is this order that we call the "gene"
- The gene is inside the nucleus. It is defined as the order of the bases (ATGC) and the number of the bases which codes for the construction of a protein in the cytoplasm.

a gene is the order of the bases on one side of the double helix

3.15 Genes

- a section of a DNA molecule is called a gene
- Genes: Carries information which forms a characteristic of the organism, could be a blood group, petal colour (in a flower)
- The genes are located in the nucleus
- The information is passed to the cytoplasm and in the cytoplasm, the genetic information is transformed into a protein. The protein controls the production of the characteristic
- GENE(in the Nucleus) ---> PROTEIN(in the Cytoplasm)

3.14 Chromosomes

1.
- Chromosomes: are the genetic information within a cell
- Typical cell: a nucleus - when opened up, a number of chromosomes is found
- Chromosomes are composed of a molecule called DNA and this forms a shaped known as the "Double Helix"
- A section of this molecule are called "Genes" and one chromosome will have many genes (possibly thousands of genes)
- Each gene carries the information for the construction of a protein
- The protein gives us the characteristics associated with the gene, e.g. blood group - a gene controls the production of the protein which controls the production of the characteristic

2.
- Different organisms have different number of chromosomes (e.g. cat = 38, chicken = 78, chimp = 42, human = 46)
- Chromosomes are known to operate in pairs = homologous pairs
- The homologous nature is based on the length of the chromosomes
- If you go to the same "gene loci" on the homologous pair, you will find the same gene, therefore, we have two versions of each gene for one characteristic - these versions are called "Allels

3.1 Sexual and Asexual Reproduction

Sexual Reproduction:
1. Organisms that show reproduction: Sexes - male / female
2. Sexually reproducing organisms produce cells called "Gametes"= formed in the male of the sperm cell (in plants = pollen grain) and in the female of the egg cell (in plants = ovule)
3. Type of cell division that produces gametes = Meiosis - one of the effects: half the total adult number of chromosomes in the gamete cell.
In humans, total number of chromosomes: 46 per cell
In gametes, total number of chromosomes: 23 per gamete cell
Going from 46-->23 is the process of cell division called Meisosis
4. Find the process of Fertilisation - in which gamete cells (the sperm cell and the egg cell) fuse together
5. Population: variation - broad. Many differences in the individuals of a sexually reproducing population

Asexual Reproduction:
1. No such sexes exist in asexual reproduction
2. No gametes
3. No meiosis, there is mitosis in eukaryotic cells and binary fission in prokaryotic bacterial cells
in this process, the number of chromosomes is maintained constantly, a cell with 20 chromosomes will divide to produce two cells with 20 chromosomes each. The two cells are identical
4. No fertilisation
5. Small amount of variation due to mutation - mostly identical - clone

How do plants reproduce asexually?

4.10 Nitrogen Cycle

N2 - 78 - 79% of the Atmosphere (fairly un-reactive)

1) Plants:
- NO3 (nitrate) ---> Amino acids ----> Protein (required for growth)
- DNA controls growth

2) Lightning combines N2 + O2 ---> NO3

3) Plants take in Nitrate to form Amino Acids which contain C.H.O.N. ---> Proteins

4) Food Chain:
- Producer ---> Primary Consumer ---> Secondary Consumer
- The nitrogen passes through the trophic levels in feeding in the form of protein

5) Animal - Nitrogen excretion (Urea + H20 ---> Urine)
- Return of nitrogen from the trophic levels back into soil

6) Death - Decomposers:
- Take the Urine/Urea along with the decaying organic molecules making ammonia (NH3)

7) Ammonia is converted into NO2 - (nitrite) ----> NO3 (Nitrate)
- This is done by a group of bacteria by: nitrifying bacteria

8) Plants:
- In the soil a bacteria called free-living, it takes atmospheric nitrogen (in air/soil) and turn it into nitrate

- Nodules in Leguminous plants such as Beans and clover. These plants also take in atmospheric nitrogen and turn it into nitrate for the plants

9) Denitrifying Bacteria:
- They take nitrate and convert it back to nitrogen and completing the cycle.

4.9 Carbon Cycle

1) Photosynthesis:
- CO2 and H2O are combined in photosynthesis using chlorophyll and light energy is trapped and used to form organic molecules
- Photosynthesis is responsible to reduce the amount of Carbon Dioxide in the atmosphere

2) Feeding:
- Producer ---> Primary Consumer ---> Secondary Consumer
- All the organisms put CO2 into the atmosphere by the process of respiration
- The primary consumer takes in the carbon from the producer and uses it to grow
- Carbon passes along the food chain
- In each stage, each organism carries out the process of .... =

3) Respiration
- Starts with glucose and oxygen ---> Energy + CO2
- Respiration adds CO2 to the atmosphere

4) Decomposition
- All of the organisms eventually die and the organic molecules that remain are broken down by the decomposers (bacteria and fungi)
- This results to the release of Carbon Dioxide into the atmosphere

5) Combustion
- Fossil fuels (oils and coals) -----> C02
- examples: industrial and motor vehicle (e.g. cars, lorries, aeroplanes etc.) where they combust fuels for their movement
- combustion occurs in the environment naturally (e.g. lightning striking vegetation = forest fires and grassland fires)

4.14 Enhanced Greenhouse Effect

1) Pollution:
- molecules such as CO2, CH4 and water vapour (all Greenhouse gasses) = increase in concentration in their upper atmosphere
- consequences: The infra-red light from the planet surface will be increasingly re-emitted backwards towards the surface rather than escaping into deep space.
- consequences of this = raise the average global temperature = global warming
- consequences of global warming:

• Melting of ice-caps in the polar regions = raise sea levels, Ocean currents changed, Change the way which winds are generated
• Deserts would expand
• Carnivorous forest distribution would change = Changes in the distribution of the worlds biomes to the major vegetation ecosystems
• Climate change

4.13 Greenhouse gases

1) Human activity: burning of fossil fuels - from factories, vehicles and domestic combustion of fossil fuels
- Results in the formation of more CO2 (Greenhouse gases), NO2 (Greenhouse gasses) and SO2

2)Farming:
- Animals (Cows) emit methane gas to the atmosphere which makes up 9% of the atmospheric gases. Significant contribute to the Greenhouse effect.

3) Evaporation - of H2O into water vapour
- Cloud are a significant contribute to the Greenhouse effect

4) Refrigeration/Solvents/Propellents - CFC
- CFC - combination of Chlorine, Florine and Carbon (e.g. CCL3F) it is well associated with the absorption of UV Light and catalyzing the breakdown of the O-zone layer

4.12 Greenhouse Effect

a) UV Light from the sun - short wavelength or high energy
b) 50% of the light is reflected back out into space the main cause of this are things like clouds
c) Absorption on the outer surface where the UV Light is converted and emitted as Infrared
d) Infrared light - long wave
e) Space - heat
f) Greenhouse gasses - water vapour, CO2, CH4 etc.
- the infrared light hits the greenhouse gas
- it will absorb the energy and then re-emitts it in all directions (including downwards) = re-emitts infrared and re-distributes
- some of the gasses which goes downwards to the surface raises the surface temperature a little bit higher

Enhanced greenhouse effect:
- if we raise level of pollution gasses, they will absorb more of the infrared radiation and emits it backwards towards the earth making the temperature higher = leading to climate change

CFC:
- known for their effect on ozone layer
- 03
- CCl3F ----(sunlight)---> CCL2F- + Cl-
- catalyses the breakdown of O3 into O2
- O3 is better at absorbing UV Light than O2

4.11 Gas Pollution

1. Sulphur Dioxide - SO2 (gas)
- added to atmosphere when we have the combustion of fossil fuels in factories
- fossil fuels (coals, oils) result to SO2 gas given off
- significant contributions to SO2 production comes from vehicles
- in the atmosphere: sulphur dioxide + water vapour ------> forms sulphuric acid
- sulphuric acid is found within the water which condenses: clouds and when rains = acid rain
- acid rain effects plants and animals in variety of ways:

• the trees and plants are often burned by the direct effect of the sulphuric acid on the surface.
• the top of tree dies
• causes calcium ions and magnesium ions to be leached out of the soil = the plant cant obtain calcium and magnesium and resulting to the leaves going yellow and the plant cant grow
• acid precipitation from streams which will form into the lakes. This reduces the pH making it acidic. Releases aluminium ions and this effects fish
• the aluminium causes thickening of the mucus that lines the gills of a fish and reduces the fishes ability to take oxygen from water = the fish suffocates and it dies

2. Carbon Monoxide - CO

- produced when fossil fuels (coal, gas) are burned with insufficient oxygen

- it combines with haemoglobin inside red blood cells and forms a molecules called carbaminohaemoglobin = blocks haemoglobin from carrying oxygen

- reducing oxygen circulation

- toxic and too much CO can be fatal

- difficult to get the CO to be released from the haemoglobin

- carbon monoxide pollution

4.7 Energy Efficiency

The diagram is a pyramid of energy.
- of the 100 percent of the producer, only 10 percent make it to the primary consumer
- of the 100 percent of the producer, only 1 percent make it to the secondary consumer.
Question: what are the causes of the losses that we are seeing?

Simple food chain (e.g.)
1) producer ( grass ) 100 Kj eaten by the herbivore
2) primary consumer ( mouse ) since 10% - only 10 Kj of the original will become part of the mouse's body and tissues.
Why? = The mice have to walk around and find their food - carry the process of respiration. Not  all of the 100 Kj of energy is available to the mouse e.g. mice cannot digest cellulose so the plant cell wall cannot be digested and the energy is lost in the form of feces. Therefore, 90Kj of the energy is lost through respiration and undigested food
3) secondary consumer ( owl ) - will only be able to assimilate 1Kj. When the owl eats the mouse, only one percent will make it this far. The losses to the owl are = respiration, energy for movement, energy for flight, energy for digestion. However, some energy is also lost in the form as feces.

All organisms will finally die.
They will be broken by the micro-organisms = decomposers

4.6 Energy and Substances in Food Chains

Bush Grass = Producer
Impala = Primary Consumer
Leopard = Secondary Consumer
Lion = Tertiary Consumer

- Producer: converts light energy into chemical energy. The chemical energy takes the form of organic molecules including: carbohydrates, proteins and lipids. These molecules, which are called food, are composed of:
C-H
C-O
C-C
O-H
C-N
bonds.
- These bonds all represent energy
- Carbon, Hydrogen, Nitrogen and Oxygen are the substances/matter

- As bush grass carries out photosynthesis it creates the organic molecules which are the substances and contain the energy which was fixed from sunlight, now in the form of chemical energy.
- The impala consumes this for: respiration, growth and life processes
- When the leopard eats the impala, these molecules are passed on and re-organized into leopard form, and so on...

Substances/Matter and the energy which is in the bonds between the elements are passed from each stage in the food chain.

4.5(a&b) Food Chains and Food Webs

4.5a Food Chains 



Food Chains link together:
Producer ----> Primary Consumer ------> Secondary Consumer -----> Tertiary Consumer

• Only one organism per trophic level
• You cannot show an organism being an omnivore / cannot show organisms feeding at more than 2 trophic levels
• Food Chains show the flow of matter and flow of energy

4.5b Food Webs




The food web allows us to provide a better description of the ecosystem (ecosystems are community of organisms interacting) In this case interacting = feeding

Feeding at different trophic levels:
consequences
- organisms can have multiple predators
- may be feeding on multiple pray
- resulting to the food chains becoming linked.

4.4 Trophic Levels

- Tropic = feed
- In the example:

• the carrot plant is doing the photosynthesis - - - - - in ecology terms - - - - - Producer (light energy and turning it into chemical energy)
• the carrot fly is eating the plant = herbivore - - - - - in ecology terms - - - - - Primary Consumer (chemical energy of the plant into chemical energy of the fly - change in the form of the chemical energy)
• the flycatcher eats the fly = carnivore - - - - - in ecology terms - - - - - Secondary Consumer (again, changing the chemical energy from one form to another)
• another carnivore eating another carnivore = top carnivore. - - - - - in ecology terms - - - - - Tertiary Consumer (Chemical energy from one form to another)

At some stage, they all die.

At this point, decomposers break the complex molecules down into nitrates and phosphates. 

fungi and bacteria are an example of decomposers.

4.3 Quadrates Samples

For this example, the habitat is sandunes:
The sample has to be:
- Random - so it is not biased
- Representative - have to take a sample large enough that the estimated population is as close to the true population as possible.

How to do this:
1) Set up a grid system across the field which will work like the x, y co-ordinates of a graph. The grid has to be equal sizes.
2) Place the quadrates into the squares. Using random numbers. (The random number generates a number for the x co-ordinate and the y co-ordinate
3) Count the number of daises in that square

Representative Sample
- the bigger the better.
- Around 10 quadrates / 10% actual area
- Draw a table with two columns consisting of Quadrate and Number of Daises
- Add up the column: number of daises
- Divide by the number of quadrates
= this will give us the number of daises per m-squared

Using this technique we can estimate the population of daises in the field and also use this technique to compare the number of daises in two or more different areas.

4.2 Quadrates

Sand-dune Ecosystem - it is made up of a number of populations which form the community and the habitat

The fence line running in the middle splits the sand-dune area into: GRAZED and UN-GRAZED by cattle. Therefore, there are two different areas within an ecosystem.

How to study the populations in the different sides: Count the number of individuals in the population.

Quadrating - when you separate land into squares using metal, wood and string (From 0.25m x 0.25m up to 1m x 1m)

It is used to sample the area and count the number of individuals inside the grid. This will be repeated a number of times = Estimate of the population size

"Quadates are a method of sampling different locations so that populations can be compared in the two different locations"

4.1 Ecosystems

Ecosystem: 

Community of organisms:

It is made up of population of difference species and they are interacting.

Population: Number of individuals of a particular species

Species: Organisms that reproduce to give fertile offspring

Habitat (Abiotic - non biological factors):
1. Daylight / Dark
2. Temperature
3. Rainfall
4. Humidity
5. Slope of the land

All of these factors are non biological factors.


- the common interaction is feeding


"A ecosystem is a community of organisms in a particular habitat. Community is made up of different populations of the different species interacting within that habitat"

Plants and Flowers Around The School

Flowers are colourful and have a sweet scent to attract insects. Some of the leaves have larger surface areas than others. Moreover, some plants are able to live in water.

Photo Credit: Michelle :)