2.75 Urine

• Urine contains salts, water and urea.
•  Water and salt particularly affects the composition of the tissue fluid. This is called osmoregulation.
• The removal of urea is part of the process of excretion of metabolic waste.
• The composition of urine varies depends on the condition of each person, both externally and internally. 

2.74 ADH

• Anti-diuretic hormone ( anti-divretic hormone) is produced in a region of the brain known as the hypothalamus. Like all hormones it flows through the blood stream and the 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 blood more or less concentrated to keep the tissue fluid isotonic.
• ADH targets the collecting duct and the effect of ADH is that it allows more water to come out of the collecting duct
• We know that water selective reabsorption happens in the collecting duct but ADH can increase the amount of water going into the blood.
• ADH makes the collecting duct walls more porous so that more water can escape from the collecting duct and this water goes back to the blood. 
• The consequence of ADH secretion is that the urine would be more concentrated and have a lower volume.

(credits to daniel)

2.73 Glucose reabsorption

Selective reabsorption means that a molecule will be selected ( glucose) and the reabsorption refers to idea that the glomerulus filtrate will go back to the blood.

• Filtration occurs in the bowman's capsule and the glumerulus filtrate will contain the molecule glucose (and many others e.g. water, salts, amino acids and urea).
• Water is selected back into blood stream at collecting duct where the urine is passed down into the pelvic region.
• At the end of the nephron is urine and normally urine does not contain glucose.
• If we find glucose in the urine it is a condition known as diabetes.
• In the first proximal convoluted tubule glucose is removed and taken back to blood.

2.72 Water re-absorption

• The blood went through ultrafiltration under high pressure in Bowman's capsule and gumerula filtrate ( where this tube contains glucose, water, salts and urea) 
• When the filtration occurs it will filter out too much water and as the filtrate passes along the tubule here. When it reaches the Collecting duct as the filtrate pass through the collecting duct what happens is that water is removed from the filtrate.
• The water is then returned to the blood vessel and will go back to the blood stream.

Selected reabsorption occurs in the collecting duct.

2.71 Ultrafiltration

Nephron carries out the filtration of our blood, which will result into filtered blood and urine.

Urine is composed largely of water, salts (Sodium chloride, etc.) and urea (which contains toxic nitrogen waste of the body) which will going to emerge at the bottom of the tube to the pelvic region.

The first process starts at the bowman's capsule, and the process is called ultrafiltration - the filtration of molecules.

• Blood arrives in the kidney through the blood vessel called afferent arteriole where the blood is under high pressure.
•  Blood vessels then started to branched and became very much slower into twisted parts called glomerulus. 
• The blood then comes out through the blood vessel efferent arteriole in which the diameter of this vessel is smaller and more narrow than the afferent arteriole's. The consequence of narrowed vessels is the increase of blood pressure. 
• The high pressure forces the liquid (plasma) and plasma contains all the substance contained in blood for example water, salts, amino acids, glucose and urea. These are all forced out from the blood into the space, the inside of the bowman's capsule.
• When the plasma is forced into bowman's capsule, we call this filtrate and because it is in the glomerulus we call this glomerula filtrate.
• The blood has been filtered due to high pressure because of the smaller area of the blood vessel.

2.70 Nephron Structure

• Nephron is the functional unit of the kidney. The part that does the filtration and of the composition of blood.
• The aorta brings blood and through the renal artery reaches the kidney 
• The waste which is the urine then goes through the ureter to the bladder.
• The filtered blood exits the renal vein and return to the vena cava. 

If we slice through the kidney we see different colored region, the lighter colored region is called the cotex and the inner, slightly colored region is called the medulla and the lighter colored space is the pelvic region.

•  In this space it is where the urine collects and drains down the ureter.
•  The region of the different color is because the kidney is made up of millions of tubes.
•  The tube starts on the edge of the medulla and moves directly upwards through the medulla and up through the cortex and then will reach a dead-end and is called the bowman's capsule.
• The tubular structure is called the nephron
  
  

In this diagram  is the Nephron structure 

• The tube is made up of twisted section called convoluted tubules and the tube which connects the convoluted tubules into the pelvic region is called the collective duct. 

• The part the dips back into the medulla is called the Loop of Henle

• The Bowman's capsule is the dead end structure in which contains tight knot blood vessels called glomerulus.

• The first twisted section is known as the proximal convoluted tubules (PCT).

• The second twisted section is know as the Distal convoluted tubules (DCT).

It is the arrangement of the nephron which gives us the difference in color between regions in the kidney. There are millions of nephron in a single kidney. 

2.69 Urinary system

In the urinary system 

•  Two kidneys the right and the left each with its own blood supply carrying out the process of filtration, osmoregulation, and excretion. 

• From each kidney there is a tube leading to the bladder which is called the ureter. 

• The urine stored in the bladder travels to outside through the urethra and down through the vagina or the penis.

2.68b Osmoregulation

Osmoreuglation - Osmo refer to Osmosis, regulation refer to control.

We do not want it to be too concentrated ( Hypertonic) and dilute ( Hypotonic) tissue fluid .We want to keep the tissue fluid isotonic (the amount of water into is equal to the output) so that the cell will remain size shape and same function which is achieved by controlling the composition of blood. 


The kidney is the organ which controls the composition of blood. 
Blood circulates through our kidney and excess water or salt is removed and excreted through the ureter here by controlling the content of water and salts in the blood, the kidney can keep the blood and therefore the tissue fluid can be maintained as isotonic which maintains the function of the cells.

2.68a Excretion

To illustrate this 
we show the excretion of urea which contains nitrogen which is toxic to the body -The amino acids are used for growth and excess amino acids needs to b removed

• Blood circulates to the liver and the amino acids are broken down and converted to a molecules which we called urea.
• This re-enters into the blood stream and which then enters both kidneys.
•  The kidneys will filter the urea from the blood and the urea will be added to water to form urine and travel down the ureter to collect in the bladder which is stored there as the form of urine. 
• The filtered blood travels back to the blood stream without any urea.

2.67b Human organs of Excretion

2.67a Excretion in plants

1. Photosynthesis absorb light energy and turn CO2 + H20 -> C6H12o6 + O2 (  where O2 is the Excretion)


2. Aerobic respiration


                       Enzyme            
C6H12O6 + 02 ------------> ATP + Co2 ( excretion) + H20


Plants excrete Oxygen and Carbon Dioxide depending upon the process it is doing.

3.10 Menstrual cycle

Oestrogen and progesterone are both hormones, which is produced in the structure called endocrine gland. Hormones will travel through the blood to the target tissue, where the hormone will have effects on.

The ovary is the endocrine gland for (produces) oestrogen that will travel through the blood stream to the lining of the uterus.

The effects of estrogen include:

1. The lining of uterus (wall of endometrium) thickens

2. Flows through the blood stream to out brain and brings the release of sex hormone (LH). It reaches its peak by day 13 of the cycle and causes the ovary to release an egg into the oviduct, where it is possible for fertilization to occur. 

During this first half of menstrual cycle, a circular structure becomes larger and larger. Inside this falloco is the egg. The cells around the fallocal are producing oestogen. It reaches it maximum size by day 13 and causes its wall to rapture and the egg is released. 

LH causes ovulation, the release of the egg.

Now that the fallico is released, the now emptied structure changes its function and develops into the yellow color. This gives us the name corpusinteum that produce progesterone. 

Progesterone travels through the blood stream to the lining of uterus. 

3. This prevents the lining of uterus from breaking down. This makes it possible that the fertilized egg then can plant into the wall of endometrium and develops into pregnancy. 

4. If no fertilized egg is planted into the wall of endometrium, then it will break down and form what we known as menstrual period/bleeding. 

This mark the end of one menstrual cycle. When the lining is broken down completely, the whole process would repeat. 

(credits to michelle biology)

3.34 Causes of Mutation

Mutation is the change in base sequence of the genes which creates new alleles.

Causes:

• Radation - Xrays or sunshine (UVB) in this case of UVB this can cause a mutation which leads to skin cancer

• Chemicals - effects of tars and tobacco which causes a change in the base sequence which can also lead to cancer.

Chemicals which cause mutation are called mutagens and those that cause cancers are called carcinogen.

3.33 Antibiotic resistance

An example of this:

Staphlococcus aureus can lead to skin and lung infections.
People with this bacteria can be treated with Methecilline Antibiotics which can kill Staphlococcus aureus.  The Staphlococcus aureus that can be killed by this antibiotic is called the susceptible form. MSSA (Methecilline susceptible Staphlococcus aureus).

What happened was there was a random mutation to the geno of Staphlococcus aureus and when the antibiotics Methecilline is applied it doesn't die and this is called the resistant form. (Methecelline Resistant Staphlococcus aureus)

The mutation has created genes that allowed the bacteria to break down the antibiotics, resisting it so it  can survive. As antibiotics are used across time this type of bacteria increasingly surivives and becomes more common. In time this has become a serious problem in hospitals.


(Credits to Daniel biology)

3.32 Types of mutation

New alleles can be: beneficial, neutral or harmful.

Example of 


Beneficial mutation might be to improve an efficiency of an enzyme. 


Harmful mutation might be a production of an enzyme that does not work


If the mutation has no particular effect, we call it a neutralmutation. 
Although the neutrality may change due to environmental change which can lead to harmful or beneficial mutations.

3.31 Evolution

Describe the process of evolution by means of natural selection.

• Evolution can be a change in the form of organisms
• Evolution can be a change in the frequency (how many) of alleles.

Natural selections is the mechanism of evolution and was first proposed by Charles Darwin.


Example:

A bacteria staphlococcus aureus which can lead to skin and lung infection is introduced.

The original form of such bacteria is sustained to be kill by methecilline, which is a type of antibiotic.

 (They are susceptible to the antibiotic.) 

What happens is that a random mutation to the genome of the bacteria allowed us a characteristic of 'breaking down methecilline.' This means that it is no longer killed by the antibiotic. This new form is called the Resistant form, MRSA.

[Refer to definition number 1 of evolution]

Because the MRSA is resistant to the antibiotic, they became increasingly common (increase in frequency of the allele) 

[Refer to definition number 2 of evolution]

Two features of natural selection (process not a thing):

1. Random mutation - produce MRSA form 

2. Non-random selection - due to anti-biotic which is selecting the MRSA to survive and MSSA to be selected and killed

3.30 Mutation

• The base sequence ( A,C,T,G,A,A,C,C) of a DNA is what constitute the gene. 
• The form of the gene is called an allele.
• Certain events and certain processes can result in a change in the base sequence .

->  This change create a new version of the allele  and it is possible that this process will result in an entirely different protein and therefore creating an entirely different phenotype ( how it looks).

The reasons why dominant alleles and recessive alleles exist is because of this process.

3.29 Species Variation

Every individual has a phenotype and the appearance for an individual for any of the characteristics is because of their genotype which is be variant to various degrees accordingly to the environment. 

Individual Phenotype = Genotype + Environment

Differences in the appearance of the indiviuals in an species is because they have different genotypes and they are surviving and living in different environments.

Vpop = Vgeneration + Venvironment

Example to this :


In the first example it shows variation that depends entirely on the genotype with no role of the environment. For example the blood groups.

In the second example it shows where the variation depends on the environment. With one example such as height, one might have been inherited the genotype to be short, however, a good diet may affect his height.
In the third example, it shows a variation in population which depends entirely on the environment. Genes have no roles to play here, for example, languages.

3.20 Pedigree diagrams

Pedigree can be use to interpret that the affected condition is caused by dominant or recessiveallele. 

3.21 Genetic Probabilities

Crossing parents (RR) and (rr)

Crossing heterozygous parents (Rr) and (Rr)

3.18c Codominance

Codominance refers to a relationship between two alleles of a gene in which both phenotypes of the genes are visible and do not over power each other in phenotype. 

This happens when both alleles are dominant. 

The offspring will result in an unusual third phenotype as the parents both contribute to the phenotype. The offspring's genotype would be a heterozygous of both dominant alleles. 

3.19 F1 x F1 Cross

PART A

PART B 

3.18 Phenotype and Genotype

Part A

Part B 

3.2 Fertilisation

• The process of fertilization begins with the adults male and female.
• The cells in testis and in ovaries have a complete cell of chromosomes                                                      - 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 (there are 23 chromosomes in the sperm cell and 23 chromosomes in the egg cell)
• During sexual reproduction the two cells are brought together and joint/fused together, so forms 1 cell. This process is know as fertilization. Which involves the combining of half set of chromosomes and another half set of chromosomes to make a full set of chromosomes (n+n=2n/in humans 23+23=46)
• This cell is known as a zygote.
• We have a combination with a male and female chromosomes. This cell then goes through the process of cell division called mitosis, in which the cells will divide to get 2 cells, they will both contain 46 chromosomes. They will then divide. All cells contain 2n diploid number.
• When we have sufficient cells, this will then be called an embryo.
• This principle holds truth for all sexually reproducing organisms but the numbers are for human only

credits to Daniel :)

3.9 b) Structure and Function of a Female reproductive System

Ovary : where Meiosis occur and production of eggs

Oviducts : carry eggs to uterus  and where fertilsation occur in here.

Uterus : wall made from muscle - will stretch during pregnancy and contract during giving birth

Lining of uterus : Accept and develop the fertilise eggs which will be develop here to embryo -> child
                         - Development of placenta

Uterus space: - Embryo develop to unborn child
                      - Both sperm cells and egg cells move

Cervix: entrance to uterus

Vagina : Collect the sperm cells and allow them into the cervix
             - Penis is introduced here

3. 9 a) Structure and function of Male reproductive system

Bladder : Store Urine

Testis : To carry out the process meiosis -> produce gamete = sperm cell

Epididymis: Store sperm cells

Vas deferens : Carry sperm sell to penis during sexual stimulation

Prostate : Contains 20%-30% volume of semen and is known to carry sugars and is alkali

               - The alkali is to neutralize the acidic secretion of the vagina

Seminal Vesicles : produce sugar based alkaline substances and contain 70% volume of semen

Urethra : Common tube which join the left and right testis and Vas deferens

               - Carry Semen and Urine down to Penis

Penis: Carry sperm cells into Vagina during sexual intercourse

3.12 Amniotic fluid

-Surrounding the uterus space is the amniotic fluid where it can protect the embryo


-This is because the fluid which is largely water can not be compressed. If we squeeze the fluid, it absorbs the pressure. 


- Any force applied to the uterus wall will absorb the pressure and prevent damage to the unborn child.

3.11 Placenta

Role of Placenta

-  When the child is in the uteris, they cannot digest or breath or excrete. The child obtain nutrition by the umbilical cord of the placental structure growing out of the embryo. 


- The blood vessel inside the placenta are the child blood's vessel include arteries and veins.


-  The placenta grows into the wall of the Uterus of the mother. During pregnancy, the mother continues to eat which means that there will be amino acids, glucose and fats in the blood which will cross through into the childs blood at the placenta then taken into the child. 


- To make this efficient, the Placenta have a large surface and a thin barriers


- The baby then produces molecules back to the mother, which is things like carbon dioxide and urea.

3.24 Mitosis

Mitosis is a form of cell division -> result in growth occurs by increase of numbers of cells


Diploid (2n) = number of chromosomes 


Cell will divide in 2 cells each with a nucleus where they both will have diploid nucleus = Cell identical(1. Same number of chromosomes
2. Same set of chromosomes)


Copy of chromosomes = DNA replication ->creates 2 Copy of the each chromosomes which it hold together by the centro-mere. 


Chromosomes will be pair = ' pair of chromatids'


DNA replication take place in the nucelus while it still intact = INTERphase of the cell cycle


Stages of mitosis 


1.Prophase = The break down of nucleus  ( pair of chromatids are visible)
2. Late Prophase = After the nucleus gone, the protein in the cell called spindle extend one pole of the cell to another. 
3. Metaphase = The pair of chromatids move towards the spindle and join one of the spindle fibre by the centro mere. 


4. Anaphase = The Spindle fibre shorten and pull the chromatics apart each other towards each pole. ( separation of the pair of chromatic)


5. Telophase = The nucleus reformed around the chromosomes = new nucleus. Shows the formation of two nuclei at opposite ends of the cell.


6.CytoKinesis = Cell splits into 2. (Not part of mitosis) 

3.16 DNA and Genetic information

There are four different types of bases: adenine (A) with thymine (T) and cystosine (C) with guanine (G).

The bases are used to holds the double helix together in the molecules. Base pair is the pairing between
adenine - thymine / guanine - cytosine to held the double helix together.

Bases order have a sequence ....
A C T G A A C C A G = GENE

Genes is equal to the number and order of bases.

3.15 Genes

Characteristic of DNA = Doublehelix


Section of the chromosomes = gene


Gene carries out the characteristic of organism eg. blood group, petal colour.


The gene are located in the nucleus and the information pass to the cytoplasm where the genetic information transformed to the protein.


This Protein controlled the characteristic of the organism.

3.14 Chromosomes

• Chromosomes are the genetic information within a cell. 

• The chromosomes are composed of a molecules called DNA (DeoxyriboNucleic Acid).

• Section of the chromosomes are called genes. 1 chromosones will have many genes.

• Each genes carry the information for the construction of protein.

• protein gives us characteristic association with the gene eg blood.

• Different organism have different amount of chromosomes                                                                                                                 
• Chromosomes operates in pairs = Homologous pairs.

The gene loci = same gene

characteristic has 2 version of each gene = called Alleles

3.1 Sexual and Asexual reproduction

Sexual reproduction

1. organism that show sexual reproduction show sexes, which we can define as male and female
2.they manufacture cells named gametes which take the form in a male as a sperm cell. In the female it takes shape as a egg.
plant ---> sperm cell is called pollen grain
---> egg cell is called ovule
3. the cell division that produces gametes is called meiosis
affect of meiosis is half the total of adult chromosones in the gamete cell.
Humans ---> total number of chromosones in cells is 46
in gametes the total number is 23 and from going to 46 to 23 is happening by the process called meiosis.
4. in sexual reproducing population there is the process called fertilisation, this is when the gametes cell of the male and female fuse together.
5.in the population we find variation (difference), which is broad

asexual reproduction 

1. asexual reproduction have no sexes
2. populations have no gametes
3. no meiosos but there is mitosis in nucaritotic cells and binary fission
in these cells the chromosones remain constantly
4. there are no gametes there is no cell fusing
5.this population shows small amount of variation due to muatation
and if they are identical know as a clone


( Credits to Jesper Kwant Corrected by Numob <3)

4.9 Carbon Cycle

1. Photosynthesis
Co2 + H20  are combine in photosynthese using clhorophyll to trap the light energy to make glucose and oxygen.


Co2 come from atmosphere. 


Photosynthesis when occur is responsible for reducing the atmospheric Co2.


2. Feeding - passage of carbon in the different trophic levels.
 Higher trophic levels will take up the lower trophic levels carbon  and travel through the food chain . Use carbon for growing.
eg. Producer -> Primary consumer -> Secondary 
consumer


3. Respiration - It adds Co2 to the atmosphere.
All organism give off Co2 to the atmosphere by respiration.


4.Decomposition -
All of the organisms will die at some point and the organic molecules are broken down by decomposer organisms (bacteria, fungi) -> carbon dioxide being released back to the atmosphere.


5. Combustion - 

• fossil fuel ( oils and coals) are combusted to release CO2. -> mainly by Industrial and vehicles
•  Environment naturally -> lighting striking plants ->forest fires / grassland