2.75- Urine

Recall that urine contains water, urea and salts

• Urine contains water, urea and salts
• Salts and urea are removed by Osmoregulation to maintain to isotonic tissue fluid with the cells
• The removal of urea is a part of excretion of metabolic waste 

2.74- ADH

Describe the role of ADH in regulating the water content of the blood


ADH- Anti- Diuretic Hormone

• It is produced in a region of the brain known as the Hypothalamus
• It flows through the blood streams to the kidney
• Its effect is to control and alter the quantity of water in blood
• The tissue fluid should be isotonic with the cells
• ADH targets the collecting duct
• It allows more water to come out of the collecting duct
• ADH makes the collecting duct walls more porous
• Consequences of ADH- urine becomes more concentrated and the volume decreases

2.73- Glucose Re-absorption

Understand that selective reabsorption of glucose occurs at the proximal convoluted tubule


Selective Re-absorption- 

• A molecule is selected and is reabsorbed into the blood
• The molecule is removed from the blood and then it is put back in
• Normally, there is no glucose in urine
• If there is glucose, it could result in the person having diabetes
• In the first convoluted tubule, glucose is removed and reabsorbed into the blood

2.72- Water Re-absorption

Understand that water is reabsorbed into the blood from the collecting duct

• When the ultrafiltration occurs in the Bowman's capsule, too much water is filtered.
• The water is removed from the filtrate
• It is then added into the blood vessels
• This is called selective reabsorption

2.71- Ultrafiltration

Describe ultrafiltration in the Bowman’s capsule and the composition of the glomerular filtrate


The filtration of the blood takes place in the Nephron. There are two products- Filtered blood (clean) and the waste (urine).
The urine (water, salts and urea) drains into the bladder from the pelvic region.

• The blood arrives in the kidney through the Afferent Arteriole
• The Arteriole begins to branch off and create a twisted knot-like structure Glomerulus
• The diameter of the Efferent Arteriole is smaller
• This creates a high pressure
• Plasma (water, salts, amino acids, glucose and urea) forced out of the blood vessel and into the inside of Bowman's capsule
• This is now called the Glomerular filtrate
  

2.70- Nephron Structure

Describe the structure of a nephron, to include Bowman’s capsule and glomerulus, convoluted tubules, loop of Henlé and collecting duct

Nephron-  The functioning part of the kidney, it does the filtration and the controlling of the composition of the blood.
Bowman's capsule- The dead end to the Nephron
Proximal Convoluted tubule- The first twisted section
Distal Convoluted tubule- The second twisted section
Glomerulus- Filters the blood and is surrounded by the Bowman's capsule
Loop of Henlé- Leads the Proximal tubule to the distal tubule
There are millions of Nephrons in the kidney.

2.69- Urinary System

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

• 2 Kidneys- Carries out the process of excretion, filtration and osmoregulation
• 2 Ureters- Carries urine to the bladder
• Bladder- Stores urine
• Urethra- Urine is conducted out of the body through the urethra

1- 2 Kidneys

2- 2 Ureters

3- Bladder

4- Urethra

2.68b)- Osmoregulation

Understand how the kidney carries out its role of osmoregulation


Osmo- Osmosis
Regulation- Control

• The tissue fluid must be isotonic (equal amount of water going in and out) so that the cells retain their shape and size and are able to function
• Blood circulating into the tissue may be too concentrated (hypertonic tissue fluid) or may be too dilute (hypotonic tissue fluid)
• To keep the tissue fluid isotonic, the composition of the blood must be controlled by the kidney
• Excess water and salts can be removed and excreted through the ureter to control the composition of the blood
• This would mean that the tissue fluid could be kept isotonic with the cells cytomplasm

2.68a)- Excretion

Understand how the kidney carries out its role of excretion 

• Kidney excretes the urea ( contains Nitrogen- toxic and can't be stored)

1. Blood circulates to the liver and amino acids are broken down into urea
2. Urea circulates to the kidneys and is filtered from the blood
3. The urea is added to water to form urine
4. Urine drains down the ureter to collect in the bladder

2.67b)- Human Organs of excretion

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

1. Lungs- Carbon dioxide 
2. Kidney- Excess water, Urea (Waste from amino acids) and salts
3. Skin- Water, Salts and urea (not much)

Metabolic waste- Carbon dioxide, Water, Urea and Salts

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 a leaf


Photosynthesis: 
CO₂ + H₂O ==> C₆H₁₂O₆ + O₂

• Oxygen is a waste molecule and is an example of excretion

Respiration:

 C₆H₁₂O₆ + O₂ ==> ATP+ CO₂ + H₂O

• Carbon dioxide is excreted by the plant as it is a metabolic waste

3.34- Causes of mutation

Mutation- change in base sequence

1. Radiation
• Ionising radiation (x-rays, gamma rays)
• UV-B rays which can cause skin cancer
2. Chemicals-  
• Tars in tobacco- causes cancer
• Chemicals that cause mutations are called Mutagens
• Chemicals that cause cancer and mutations are called Carcinogens

3.33- Antibiotic resistance

Understand how resistance to antibiotics can increase in bacterial populations

• Staphylococcus aureus causes skin and lung infection
• Can be treated with methicilline (antibiotic which kills Staphylococcus aureus)
• The susceptible form of Staphylococcus aureus is the form which can be killed by the antibiotic
• There was a random mutation to the genotype of Staphylococcus aureus
• This didn't die when given the antibiotic, also known as the resistant form (MRSA)
• The mutation is helpful to the Staphylococcus aureus as it survives the antibiotic

3.32-Types of mutation

3.31- Evolution

Describe the process of evolution by means of natural selection

Evolution:

• Change in the form of organisms
• Change in the frequency of alleles

Natural selection is the mechanism of evolution. (first proposed by Charles Darwin)

Eg:
Staphylococcus aureus which causes skin and lung infection

• The original form is susceptible to to being killed by antibiotic. This is known as MSSA
• It then, by random mutation, forms a form which is resistant to antibiotics. This is known as MRSA
• The change to MRSA caused the change in the frequency of the alleles and the frequency of the resistant form increased

3.30- Mutation

3.29- Species variation

Variation= differences in phenotypes
Phenotype can be modified by the genotype + environment

1- Discontinuous

2- Continuous

3- Entirely depends on environment  

3.20- Pedigree Diagrams

3.21b)- Genetic Probabilities

3.21a)- Genetic Probabilities

3.18c)- Codominance

3.19b)

3.19a)

3.18a) and b)

Genetics

3.2- Fertilisation

Understand that fertilisation involves the fusion of a male and female gamete to produce a zygote that undergoes cell division and develops into an embryo

• The cells in testis and in ovaries have a complete cell of chromosomes and this is called diploid (2n) which is a complete set of chromosomes and for human it is 46
• The cells divide to form cells with half sets of chromosomes, this type of cell division is called meiosis this makes the cell go from a diploid number to a haploid number(n) which is a 1/2 set so in humans it is 23
• During sexual reproduction the two cells are brought together and joined together, so it forms just 1 cell. This process is know as fertilization and it involves the combining of half set of chromosomes and another half set of chromosomes to make a full set of chromosomes (23+23=46)
• This cell is known as a Zygote
• This cell goes through Mitosis in which the cells divide but they all contain 46 chromosomes
• It will be called an embryo when we have sufficient amount of cells

3.9- Reproductive systems

Recall the structure and the function of the male and female reproductive systems


Male reproductive system:

• Bladder
• Stores urine
• Testis 
• Carries out Meiosis which produces the male gamete, sperm cell
• Epididymis
• Store sperm cells
• Vas Deferens 
• Carries sperm cells to the penis
• Prostate
• 20-30% of the volume of the semen, contains sugars. Alkaline solution, to neutralise the acidic secretions within the vagina
• Seminal Vesicals
• Produces 70% of the semen; sugar based and alkaline
• Urethra
• Common tube that joins the left and right Vas deferens, transports semen and urine down the penis
• Penis 
• Carry sperm cells into vagina

Female reproductive system:

• Ovary
• Meiosis occurs to form the female gamete. the egg cell
• Oviduct
• Carry the eggs to the uterus, fertilisation occurs here
• Uterus wall
• the wall of the uterus, made of muscle and stretches to accomadate a pregnancy
• Uterus lining
• accepts and develops the fertilised egg into an embryo and then into a child, the placenta implants into here
• Uterus space
• Where the embryo is developed into an unborn child
• Cervix
• Entrance to uterus
• Vagina
• Collects the sperm from the penis and allows them to pass through the cervix and into the uterus

Before pregnancy the entire uterus structure is no larger than an orange.

3.12- Amniotic fluid

Understand how the developing embryo is protected by the amniotic fluid

• Amniotic fluid surrounds the embryo in the uterus
• The fluid acts protects the embryo as it is mostly water and can't be compressed
• The fluid absorbs the shock of any blow to the outside of the uterus

3.11- Placenta

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

• When the child is in the uterus, it is surrounded by amniotic fluid.
• It cannot digest, breath or excrete so it gets it's nutrients from the mother through the placenta. 
• The placenta consists of the the umbilical cord containing the embryo's blood vessels. 
• The placenta grows out of the embryo
• It grows into the wall of the uterus
• Glucose, Amino acids and fats travel through the mother's blood vessel
• These will cross into the child's blood at the placenta
• The placenta has a large surface area and the barrier is really thin to make this process efficient
• Carbon Dioxide and Urea are exchanged back into the maternal blood

Mitosis

Mitosis animations:

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html
• http://cellsalive.com/mitosis.htm

Stages of Mitosis:

3.24a-c)- Mitosis

a) Understand that division of a diploid cell by Mitosis produces two cells which contain identical sets of chromosomes

The diploid number is the number of chromosomes in the nucleus. This can be abbreviated as 2n. Humans have 46 chromosomes so 2n=46.In the process known as mitosis a cell is divided to two cells - each with a nucleus. If we look at the nucleus we will find that each one will have a diploid nucleus.We often say that these cells are 

identical sometimes described as daughter cells. (same no. of chromosomes, same set of chromosomes)

b) Mitosis is performed through DNA replication, in this each chromosome replicates itself. The two copies are held together by a structure around the center region known as the centromere. They are known as a pair of chromatids. DNA replication takes place in the nucleus while its still intact. The process of DNA replication takes place inside the nucleus while its still inact. This is known as the interphase.

 

 

c) The stages of mitosis

Observing a cell down a microscope, we would normally see a nucleus has a spherical structure and would be unable to observe the chromosomes. It is during the interphase that the process of DNA replication occurs.

When the membrane breaks down and the chromosomes become visible as a pair of chromatids= Prophase.

 

The nucleus is gone, inside the cell, there is a network of protein molecules called spindle. These extend from one pole of a cell to the other. The pair of chromatids will join on one of the spindle fibres at the centromere.

Metaphase is when the pair of chromatids are attached to a spindle fibre by the centromere, characteristic of the metaphase is that the chromatid is in the middle across the equator of the cell.

In the Anaphase the fibre shortens pulling the chromatids apart and they move to the poles of the cell. The pair of chromatids are seperated. 

The last phase is called Telophase, in which the nucleus begins to reform around the chromosomes at either end of the cell. We see the formation of two nuclei at opposite ends of the cell.

Cytokinesis is where the cell splits into two, this is not part of mitosis. Here we see the nucleus that has reformed in the anaphase, the cell is beginning to move inwards, dividing the cytoplasm in half and the 

membrane fuses across the equator to form two cells. Both of these cells contain a chromosome. 

3.16- DNA and Genetic information

Describe a DNA molecule as two strands coiled to form a double helix, the strands being linked by a series of paired bases: adenine (A) with thvmine (T) and cvtosine (C) with guanin (G)

If we look at a section of the double helix we will see bases that are close together and there are four different types of bases: adenine (A) with thvmine (T) and cvtosine (C) with guanin (G).

In the molecule, these bases are holding together the two helixes and are held together by pairing between A with T on one side and C with G on the other. These are known as the base pairs.

If we look on one side, we can see the order is ACTGAACCAG. This is the order of the bases and this is called the gene.

Gene can be defined as the order of the bases and the number of the bases. This is for the construction of the protein in the cytoplasm and this gives us the characteristic.

3.15- Genes

Understand that a gene is a section of a molecule of DNA.

A section of a molecule of DNA is called a gene. This gene carries the gene which forms the characteristic of an organism. This could be a blood group or petal colour. This information is passed to the cytoplasm and in there it   is transformed into a protein and it is this protein that controls the production of the characteristic.

Gene (nucleus)-------------->Protein (cytoplasm)

3.14- Chromosomes

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

Chromosomes:

• Contains genetic information within a cell, in a nucleus of a cell. 
• Chromosomes is composed of DNA and this forms a shape known as a double helix. Sections of this molecule are called genes. 
• One chromosome will have many genes. Each gene carries the information for the construction of a protein.
• This gives the characteristic associated with a gene. For instance- blood group.
• Different organisms have a different amount of chromosomes: 
• Cat- 38
• Chicken- 78
• Chimpanzee-42
• Human-46
• Chromosomes operate in homologous pairs and the nature depends upon the length of the chromosomes.

If we look at a gene, the position is known as a gene loci. If we go to the same position on the homologous we find the same gene loci. Therefore we have 2 versions of each gene. This version is called alleles. 

3.1- Sexual and Asexual reproduction

Describe the differences between sexual and asexual reproduction.

1. Organisms that show sexual reproduction show sexes( male/ female), no such sexes exist in asexual reproduction.
2. Sexually reproducing organisms produce cells called GAMETES (sperm/egg). In plants the sperm cell is known as the pollen grain and the egg cell is know the ovule. Asexually reproducing populations have no gametes.
3. The type of cell division that produces gametes is known as MEIOSIS. It has a number of effects and one of them is half the chromosomes in the gamete cell. In humans, the totals number of chromosomes per cell is 46, whereas, in a gamete cell there are 26 per cell (through MEIOSIS). In asexually reproducing population there is MITOSIS in Eukaryotic cells and binary fission in prokaryotic cells. In this process the number of chromosomes are maintained constantly. 
4. In sexually reproducing population, we find the process of fertilisation, in which the male gamete fuses with the female gamete. In asexual reproduction, there is no cell fusion.
5. If we examine the population of a sexually reproducing organisms we will find broad variation and in asexually reproducing populations there will be small variations due to mutations. By enlarge they are identical, this is known as a clone. 

Question: What are eukaryotic and prokaryotic cells?

4.9- Carbon Cycle

                                            
1) Photosynthesis:

• CO2+H20------>C6H12O6
• reduces carbon dioxide in the atmosphere

2) Feeding:

• Carbon passes along the food chain

3) Respiration:

• Aerobic: C6H12O6 + O2----->CO2+H20+ Energy
• Adds CO2 to the atmosphere
• All organisms are giving off carbon dioxide to the atmosphere through respiration 

4)Decomposition: 

• Organic molecules are broken down by the decomposer organisms which includes bacteria and Fungi
• This will result in the release of carbon dioxide back to the atmosphere

5) Combustion:

• Fossil fuels (Oils and coals)------------> Carbon dioxide 
• Industrial uses can contribute the amount of carbon dioxide in the motor vehicles
• Combustion can occur naturally ( forest fires)

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 its consequences

• Pollution of carbon dioxide, methane and water vapour (greenhouse gases)
• If their concentration increases then the Infra-red light would be increasingly re-emitted rather than escaping into space
• This will raise the average global temperature which is called global warming
• Consequences:
• Raised sea levels- melting of icecaps
• Changing ocean and wind currents
• This leads to climate change

This will lead to the worlds Biome distribution changing, polarised caps melting, etc.

4.13- Greenhouse gases

Human activities effecting greenhouse gases:

• Burning of fossil fuels results in the formation of carbon dioxides and nitrous dioxides which are greenhouse gases.
• Cows emit methane gas which is about 9% of the atmospheric gases.
• Evaporation of water to form water vapour, clouds are a significant contributor
• Refrigeration/ Solvents are associated with the absorption of UV light and catalysing the breakdown of the ozone layer

4.12- Greenhouse Effect

a) represents UV light from the sun (short wavelength, high energy)
b) shows that 50% is reflected back mainly by the clouds
c) shows absorption on the surface where the UV light is converted and emmited as Infra-red
d) shows the Infra-red (longer wavelength) being emitted back out
e) shows heat which is lost to space
f) represents some of the greenhouse gases like water vapour, CO2, CH4
g) Infra-red light absorbs the greenhouse gas and then re-emits and re-distributes it with some of the gases going back to the surface

The hypothesis of the enhanced greenhouse effect is that if we emit more CO2 and CH4, they will absorb more of the escaping Infra-red radiation and emit it back to earth, raising the temperature higher and causing climate change
CFC are well known for their effect on the ozone layer O3
CL- catalyses the breakdown of O3 to O2. O3 is better than absorbing light than O2 so we are basically removing the protection of the ozone layer.

4.11- Gas Pollution

• Sulphur dioxide:
• Is added to the atmosphere when the fossil fuels are combusted and also with the combustion of petrol in vehicles
• In the atmosphere, Sulphur dioxide combines with water vapour and forms Sulphuric acid which is also known as acid rain
• Effects on plants and animals:
• They are often burned by the sulphuric acid
• Magnesium and Calcium ions are leached out of the soil which means that the plants can't obtain them from the soil
• Lakes have reduced pH which causes release of Aluminium ions and this effects fish as the Aluminium causes the thickening of the mucus that lines the gills and reduces the fish's ability to take in oxygen. This kills the fish as it suffocates
• Carbon Monoxide:
• Produced when fossil fuels such as coal/gas are burned with insufficient oxygen
• Combines with Haemoglobin in red blood cells and forms Carbaminohaemoglobin which blocks the Haemoglobin from carrying oxygen which reduces oxygen circulation in the body

4.7- Energy Efficiency

The diagram is a pyramid of energy:

• Of the 100% of producer, only 10% makes it to the next level in the primary consumer
• Of the 100% of producer, only 1% makes it to the next level in the secondary consumer

Question: What are the causes of the losses that we are seeing?

Simple food chain:

1. Producer (grass)- 100 kJ eaten by herbivore
2. Primary consumer (mouse)- only 10kJ of the original will become part of the mouse's body and tissues
• This is because they have to find their own food and they carry out the process of respiration
• Not all of the 100kJ of energy is actually available to the mouse:
• Mice cannot digest cellulose so the plant cell wall cannot be digested and the energy is lost in the form of faeces(undigested material). So, 90kJ is lost through respiration and undigested food
3. Secondary consumer (Owl)- only be able to assimilate 1kJ
• The losses to the owl are respiration. Energy required for:
• Movement
• Flight
• Digestion 
• Not all of the mouse is digested by the owl and so some is lost as faeces

All organisms will finally die and are broken down by micro-organisms called decomposers.

4.6- Energy and substances in food chains

1. Producer converts light energy into chemical energy
2. This chemical energy takes the form of:
• Organic molecules
• Carbohydrates 
• Proteins 
• Lipids
3. These molecules are all food to consumers in the food chain and contain bonds such as:
• C-H
• C-O
• C-C
• O-H
• C-N
• These bonds all represent energy
• CHON (substances/matter) contain energy

• The impala consumes substances for:
• Respiration, growth and life processes 
• When the leopard eats the Impala, these molecules are re-organised into leopard form

4.5c)- Pyramids

Three types of pyramids covered:

• Pyramids of number
• Pyramids of biomass
• Pyramids of energy transfer

1. Pyramids of number
• Illustrates the number of organisms at each trophic level
• Some problems are:
• Not effective at showing energy transfer
• Effective but have some problems
2. Pyramids of biomass
• Bio= 'Living'
• Mass='g/kg'
• Based on dry mass
• Measured in kg/area (km squared)
• Hard to carry out experiments to find out dry biomass
3. Pyramids of energy transfer
• Show the movement of energy from one trophic to the next
• Cannot be inverted (Advantage)
• The reduction at each trophic level shows the measure off efficiency
• Unit of energy- J/kJ
• Unit of area- m squared
• Unit of time- minutes/seconds/years
• Problem- time consuming

• Pyramid of number> biomass> energy

4.5b)- Food Webs

Food webs can show organisms feeding at different trophic levels.

Feeding at different trophic levels:

• Organisms can have multiple predators
• They could be feeding on different prey
• This results in the food chains becoming linked

4.5a)- Food Chain

Food chain links together the:
 Producer--- Primary Consumer--- Secondary Consumer--- Tertiary consumer

In a food chain you cannot show an organism:

• being an omnivore
• feeding at 2 trophic levels

Food chains show the flow of matter and energy

4.4- Trophic Levels

Trophic = Feed

• Producer turns light energy into chemical energy
• Primary consumer changes the form of the chemical energy 
• Secondary consumer also changes the form of the chemical energy
• Tertiary consumers change chemical energy to chemical enrgy

• All organisms die and are broken down by decomposers (fungi and bacteria)
• Decomposers are important in recycling of molecules
• They often break down the complex molecules into nitrates and phosphates

4.3- Quadrates Samples

Describe the use of quadrats as a technique for sampling the distribution of organisms in their habitats

-Use quadrats to sample the population
Samples:
-Random
-Representative (Large), the bigger the better
-Random numbers (x,y co-ordinates), can be generated online
-Count the population in the square of the random x,y co-ordinates
-10% of the actual area

No. of eg. daises per meter squared= no.of daises divided by no. of quadrats

4.2- Quadrats

Recall the use of Quadrats to estimate the population size of an organism in two different areas:
Quadrating:
-Count the number of individuals in the population
-Quadrat is used to sample the area and count the number of individuals in the area
-This would be repeated a number of times to gain an estimate of the population size

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

4.1- Ecosystems

Ecosystem-- community of organisms which in a particular habitat
Community-- different populations of different species interacting within that habitat
Population-- No. of individuals of a particular species
Species-- Organisms that reproduce to give fertile offspring
Habitat (abiotic factors, non-biological):
- Cycle of daylight
-Temperature
-Rainfall
-Humidity
-Slope

Plants

Examples of plants around the school:

Some photos taken from http://danielscienceblogg.blogspot.com/

Seeds

The animal eats the apple--- The seed is in the animals digestive system---- The seed comes out of the animal when it poo's---- The seed is displaced and starts growing

Seed Coats:

3.4 Plant Fertilisation

-Pollen grains germinate and tubes start to grow
- Pollen tubes will only complete if its the same specie
- The pollen tubes go to the ovule
       -The pollen nucleus fertilizes the ovule which will lead to the formation on a zygote
       - This will grow into the embryonic plant
- Outside ovule forms a seed coat called testa
- Formation of the cotyledons (food stores for seedling, supports plant)
-Thickening of the walls of the ovary which makes fruit

 (3.3)b)- Wind Pollination:

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

·         Pollination: transfer of pollen grains from the anther of one plant to the stigma of another

·         Transfer of pollen grain from anther to the stigma through air carried by the wind

·         Adaptations of Pollination:

o    Light weight pollen grains

o    Anthers are exposed to the wind

o    Stigma- large surface area to catch pollen grains

·         Wind- Pollination:

o    No Colour

o    No Scent

o    No Food