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.