2.75 Urine

Recall that urine contains water, urea, and salts.

2.74 ADH.

anti-diuretic hormones are produced in a region of the brain known as hypothalamus it then flows through the bloodstream to the kidney. this hormone controls the concentration of blood.

this helps with osmoregulation. it affects the collecting duct and creates more pores to let more water be reabsorbed back into the bloodstream.

2.73 Glucose Absorption

glucose is is re absorbed through the proximal convoluted tubule.
this occurs before the filtrate reaches the collecting duct.
because of this, no glucose will be present in urine unless a condition is acquired eg. diabetes

2.72 Water re-absorption

the filtered blood will then move along the nephron until it reaches a collecting duct.
the filtrate which passes through the collecting duct, it's water is removed and is returned to blood vessels. this is known as selective re-absorption of water.

2.71 Ultrafiltration

Nephron - filtration of blood - filtered blood, urine

urine is composed of water, salt and urea

urea is formed in bowman's capsule, it is where the process of blood filtration begins and is known as ultrafiltration.

blood comes into nephron through an afferent arteole with high pressure which forces the plasma into the glomerulus which then filters it.

2.70 Nephron Structure

-Renal artery takes blood into kidney
-Kidney filters blood and waste is excreted as urine through the ureter to be released from the body by the bladder
-Filtered blood returns to vena cava
-Kidney consists of 3 parts the light coloured one is called the cortex, red is the medulla and the space is called the pelvic.

2.69 Urinary System

describe the structure of the urinary system including the kidneys, ureters, bladder and urethra.

each kidney has a tube that leads to the bladder called a ureter.

ureters carry urine to bladder.

bladder then sends urine through another tube called the urethra to be excreted from the body through the penis or vagina.

2.68b Osmoregulation

understand how the kidney carries out it's role of excretion and osmoregulation.

Osmoregulation: Control of Osmosis
fluids surrounding cells must be isotonic with the cytoplasm of the cells.
meaning the amount of water going in and out of the cells are equal.

threats include concentrated tissue fluid (hypertonic) or dilute tissue fluid (hypotonic)

kidneys can regulate the amount of water and salts in the blood to make sure the cells remain isotonic

2.68a Excretion

understand how the kidney carries out it's roles of excretion and osmoregulation.

kidney is responsible for excretion of urea.
urea contains nitrogen which is toxic to our body in excess amounts.
most common form of nitrogen base molecules in our bloodstream are the amino acids.
blood circulates to the liver and amino acids broken down into urea.
kidney filters urea and adds water to form urine
urine passes down to the bladder to be removed from body

2.67b Human Organs of Excretion

Recall that the lungs, kidneys and skin are organs of excretion.

Lung excretes carbon dioxide
Kidney excretes h2o, urea and salts (amino acids)
skin excretes h2o + salts in sweat. and urea

2.67a Excretion in plants

recall the origin of carbon dioxide and oxygen as waste products of metabolism and their loss from the stomata of the leaf.

1. Photosynthesis: CO2 + H2O => C6H12O6 + oxygen
2. Aerobic Respiration in plants: C6H12O6 =enz.=> ATP + CO2 + H2O

carbon dioxide and oxygen are both waste products of plants depending on whether it is from photosynthesis or respiration.

3.34 Causes of Mutation

Understand that the incidence of mutations can be increased by exposure to ionizing radiation and chemical mutagens.

Two main causes of mutation = 1. Ionizing radiation - gamma rays
- x rays
- ultraviolet rays

2. Chemical Mutagens - tar in tobacco
- cancer causing carcinogens

3.33 Antibiotic Resistance

Understand how resistance to antibiotics can increase in bacterial populations

Resistance to antibiotics can increase in bacterial populations
1. eg. Staphylococcus Aureus is treated with Methicillin antibiotic
2. MSSA = Methicillin Susceptible Staphylococcus Aureus
3. Random mutations to MRSA = Methicillin Resistant Staphylococcus Aureus
4. Non-random selection to survive and increases in population due to its resistance to the antibiotic used to suppress or eliminate the bacteria

3.32 Types of Mutation

understand that some mutations are harmful, some are neutral and some beneficial.

when a gene mutates into an allele possibilities are:
1. harmful mutation eg. non functioning enzyme
2. neutral mutation caused by environmental factors neither harmful nor beneficial
3. beneficial mutation eg. improves efficiency of organs

3.31 Evolution

describe the process of evolution by means of natural selection.

Evolution = change in the form of an organism (change in frequency of alleles)
Natural selection concept introduced by Charles Darwin.
-Random mutation that happens to be suited to the current environment.
-non random selection to survive
Natural selection is the name for this concept.

3.30 Mutation

recall that a mutation is a rare, random change in genetic material that can be inherited.

mutation changes base sequence of the gene
certain events and processes can alter the base sequence of gene and results in the production of a new protein.

3.29 Species Variation

understand that a variation within a species can be genetic, environmental or a combination of both.

Variation = differences of phenotype count/measure
Individual Phenotype = genotype + environment
Variation in population = Variation Genotypes (environment = 0)
E.g. Blood group A, AB, B, O = Discontinuous variation
Variation Population = variation genotype + variation environment eg. height = continuous variation.
Variation Population = (genotype =0) + variation environment eg. language not inherited

3.21b Genetic Probabilities

3.21a Genetic Probabilities

3.20b Pedigree Diagrams

3.20a Pedigree Diagrams

3.18c Codominance

3.19b F1 x F1 Cross

3.19a P1 x P1 Cross

3.18b Genotypes

3.18a Phenotypes

3.12 Amniotic Fluids

understand how the developing embryo is protected by the amniotic fluid

3.10 Menstrual Cycle

describe the role of oestrogen and progesterone in the menstrual cycle

-oestrogen and progesterones are types of hormones
-they are produced in endocrine glands
-they are specific to a certain tissue and affects them accordingly
-the ovary is an endocrine gland which produces oestrogen
-oestrogen affects the uterus wall by:
1. thickening the uterus wall in the first 14 days of cycle
2. oestrogen also affects the brain by making it release another hormone known as the liutenising hormone which then makes the ovary release an egg

after ovulation the follicle which once contained the egg will take on a yellow colour called corpus liuteum

this then becomes a progesterone producing gland and progesterone maintains the uterus wall thickness to prevent it breaking down.

3.11 Placenta

describe the role of the placenta in the nutrition of the developing embryo

3.9 Male Reproductive System

3.24c Mitosis 3

understand that the division of a diploid cell by mitosis produces two cells which contains identical sets of chromosomes.

mitosis consists of 6 stages:

1. interphase - dna replication
2. prophase - nucleus membranes break down
3. late prophase - chromatids move towards protein spindles
4. metaphase - centramere joins ups with spindles
5. anaphase - seperation of chromatids
6. telophase - end of mitosis

3.24b Mitosis 2

understand that the division of a diploid cell by mitosis produces two cells which contains identical sets of chromosomes.

cells which undergo the process of mitosis will divide into two cells with the same sets of chromosomes as the original.

replicated DNA are held together by a centromere

3.24a Mitosis 1

understand that the division of a diploid cell by mitosis produces which contain identical sets of chromosomes.

Mitosis describes the process of cell division, this causes a growth in the increase of cells.

3.16 DNA and Genetic Information

describe DNA molecule as two strands coiled to form a double helix. the strands being linked with a series of paired bases. adenine A with thymine T and cytosine C with guanine G

3.15 Genes

understand that a gene is a section of DNA.

each gene carries the information which defines the characteristics of the organism.

genes are located in the nucleus which are then transferred to the cytoplasm which converts the information into protein.

3.14 Chromosomes

recall that the nucleus of a cell contains chromosomes on which genes are located.

Chromosomes are composed of smaller molecules called DNA which forms the shape of a double helix.

each section of the DNA is called a gene

a single chromosome may contain thousands of genes

these genes hold the information used to produce protein

proteins give us the characteristic associated with the gene, such as blood group

different organisms have different number of chromosomes
Cat= 38
Chicken = 78
Chimpanzee = 42
Human = 46

chromosomes operate in pairs known as homologous pairs.
the nature of each pair depends on the length of the chromosome
the position of a gene is called the gene loci
if we go to the same position on the other chromosome in the same homologous, we will find another version of the same gene.

3.1 Sexual and Asexual Reproduction

describe the differences between sexual and asexual reproduction.

Sexual Reproduction -
1. Sex- male/female
2. Gametes
-male = sperm cell
-female = egg cell
3. Meiosis - half chromosomes
4. Fertilisation
5. Variation - broad

Asexual Reproduction -
1. no sex
2. no gametes
3. mitosis/binary fission
4. no fertilisation
5. variation - small

Question: What is a chromosome?

4.9 Carbon Cycle

describe the stages in the carbon cycle including respiration, photosynthesis, decomposition and combustion.

1. Photosynthesis = CO2+H2O -chl&light-> C6H12O6 + O2 = 0.03% of atmospheric carbon

2. Feeding = Producer -carbon-> primary consumer -carbon-> secondary consumer

3. Respiration = C6H12O6 + O2 -enzyme-> energy + CO2 + H2O

4. Decomposition = death of organic molecule -bacteria&fungi-> CO2

5. Combustion = Fossil fuels (oils, coals) -industrial/motor-> CO2

4.14 Enhanced Greenhouse Effect

understand how an increase in greenhouse gases results in an enhanced greenhouse effect and that this may lead to global warming and it's consequences.

Pollution: CO2, CH4, water vapour
these gases re-emit UV light back to the earth, raising the global temperature.

Consequences:
Melting ice caps -> raised sea level -> change in ocean current and wind direction -> redistribution of ecosystems -> less land due to increase of water

4.13 Greenhouse Gases

understand how human activities contribute to greenhouse gases.

Burning fossil fuels -> CO2, SO2, NO2 (greenhouse gases)
they absorb infrared light and reflect them back to the planet

Cow digestion emits methane gas -> 9% of greenhouse gases

Evaporation of water -> water vapour

CFCs absorb UV light and breaks down the ozone layer

4.12 Greenhouse Effect

Recall that water vapour, carbon monoxide, nitrous oxide, methane and CFCs are greenhouse gases.

-Photo courtesy of aufarbiology.blogspot.com

4.11 Gas Pollution

Understand the biological consequences of pollution of air by sulphur dioxide and carbon monoxide.

SO2 -> created by the burning of fossil fuels & crude oil
sulphur dioxide combines with water in the atmosphere to form
sulphuric acid.

-> Plants which come in contact with this acid will be burned.
-> Minerals from the soil are leeched by the acid.
-> When acid reaches the lake, it lowers the Ph and forms Aluminium
-> Aluminium ions in the water cause fish to suffocate
----------------

CO2 -> created by incomplete combustion

-> carbon monoxide coats haemoglobin on red blood cells
-> this prevents it from carrying oxygen
-> no oxygen = death

4.7 Energy Efficiency

explain why only 10% of energy is transferred from one trophic level to the next.

10% of the producer's energy makes it to the primary consumer and 10% of the primary consumer make it to the secondary consumer. only 10% of energy can be absorbed by a consumer of the next level because the demands of the greater consumers are more than the lesser consumers.

4.6 Energy and Substances in Food Chains

understand the transfer of substances and energy along a food chain.

Producers convert light energy into chemical energy. the chemical energy takes the form of organic molecules such as carbohydrates and protein. these molecules get passed along the food chain from producers to primary consumers to secondary consumers.

4.5b Food Webs

understand the concept of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of transfer.

Food webs are used to describe feeding patterns in the ecosystem. this allows us to show organisms feeding at different trophic levels. doing so has a number of consequences such as more predators, more prey and ultimately linking the food chains.

4.5a Food Chains

understand the concept of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of transfer.

food chains link together the producer, primary consumer, secondary consumer and tertiary consumers.

1. organism per trophic level
2. food chains cannot show omnivores
3. no organisms that feed in more than 2 trophic levels
4. shows flow of matter and flow of energy

4.4 Trophic Levels

Recall the names given to different trophic levels to include producers, primary, secondary and tertiary consumers and decomposers.

Trophic level=feeding level
producers eg. carrot (photosynthesis)=> carrotfly (primary consumer)=>flycatcher (secondary consumer)=> sparrow (tertiary consumer)
at some point, these living organisms die.
Decomposers such as fungi and bacteria recycle molecules of the living organism into nutrients.

4.3 Quadrate Samples

describe the use of quadrates as a technique for sampling the distribution of organisms in their habitats.

Quadrate samples are always random to avoid bias and representative (large samples that are closest to the actual population as possible). samples are taken by setting up a grid system on the field. number the grid like a graph. generate random numbers and place quadrates accordingly to those coordinates. bigger samples are better but 10% of the actual area is best. after that, tabulate the data to form 2 columns (quadrate number and number of organisms/metres squared). add up the numbers and divide by the number of quadrates to get the number of organisms.

4.2 Quadrates

recall the use of quadrates to estimate the population size of an organism in two different areas.

Ecosystems are made up of a number of populations which form a community and the habitat.
start by counting the number of individuals in the two different areas. this can be made easier with the use of quadrating (placing a square grid of 0.5m to 1.0m) then taking samples and counting individuals in the grid. Quadrats are a method of sampling different locations so the population may be compared.

4.1 Ecosystems

Understand the terms: population, community, habitat and ecosystem

An ecosystem is divided into 1.Community of Organisms
-population of different (species)=>organisms that reproduce to make fertile offsprings
(interactive)=>feeding
2.Habitat-abiotic/nonbiological (daylight,temperature,rainfall etc)

Cross Section Apple

Close up of Lily Pollen Grain (Diagram)

3.3b Wind Pollination

Describe the structures of an insect pollinated flower and a wind pollinated flower and explain how each is adapted for pollination.

Transfer of pollen grains in certain plants are done through air, carried by the wind. The first most common adaptation is light weight which usually comes with a wing feature to allow for faster travel through air. Anthers of wind pollinated plants hang down to become more exposed to the wind. The stigmas on the other hand, have a large surface area and most likely a feather to catch pollen grains. No attractive features are needed for this type of pollination.

3.3a Insect Pollination

Describe the structures of an insect pollinated flower and a wind pollinated flower and explain how each is adapted for pollination.

In order for pollination to occur, there needs to be a transfer of pollen grain from the anther of one plant to the stigma of another plant. Insect pollinated flowers use insects to carry pollen grains from one plant to the other. in order to do so, the plant needs to attract insects. they do this by using signals (colour petals, scent)and value (food nectares, pollen protein). The insects then drop off the pollen grains on the next plant it goes to, therefore initiating pollination.

3.4 Plant Fertilisation

Understand that that the growth of the pollen tube followed by fertilisation leads to seed and fruit formation.

Pollen grain rests on the stigma and germinates, growing a pollen tube all the way down to the ovule. The male nucleus of the pollen will fertilise the ovule leading to the formation of a zygote which then grows into an embryonic plant. The outside of the ovule forms a testa (seed coat)while the inside forms a cotelydon which is a food store for the young seedling. and the walls of the ovary becomes a fruit.

2.81 Phototropism

Describe positive phototropism of stems.

Phototropism is the growth of a plant in response to light.
Positive phototropism suggests that this growth is towards the light.
The stem of a leaf will grow in the direction where there is the highest concentration of light. if the direction of light changes, the plant will grow to whichever direction has the highest concentration of light. This is called positive phototropism. this occurence is cause by the hormone auxin.

light -> growth -> towards light

2.80 Geotropism

Describe the geotropic responses of roots and stems.

Geotropism is the growth repsonse to gravity. Observing a seed shows that the embryo of the seed grows downwards. this is called positive geotropism. A shoot of the seed grows upwards. this is called negative geotropism. Rotating the leaf produces the same effect because of Geotropism.

2.79 Plants and Stimuli

Understand that plants respond to stimuli.

Stimuli -> Receptor -> Response

Changes in the environment leads to the plant receptors detecting stimuli which is then converted into a response, usually in the form of growth. This is called a tropism. tropism involving light is called phototropism while gravity related tropism is called geotropism. connections between the receptors and the response is the plant hormones such as auxin.

2.54 Transpiration

Recall that transpiration is the evaporation of water from the surface of the plant.
Liquid --heat/sunlight--> Gas
In order for the water in the plant to turn into a gas, it will need heat. Heat is absorbed by the plant through the leaves in the form of sunlight.
excess gas diffuses out of the stomatal pores.
As sunlight enters the leaf for photosynthesis and the water is spread around the spongy mesophyll, the water is heated up by the sunlight, turning it into a gas. this occurs near the stomatal pore to allow it to evaporate out of the leaf.

2.53 Uptake of Water

Explain how water is absorbed by root hair cells.

Roots branch out over a wide surface area to find water source. The epidermis of the root is lined with root hair cells. Root hair cells branch out, also over a wide surface area. Minerals are actively transported into the root hair cell, which then allows osmosis to occur and bring water into the cell. This is because the soil water around the root hair cell is now dilute making the water move into the more concentrated area inside the root hair cell.