Thursday, October 27, 2011

2.69 Urinary system

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

1. Each kidney has its own blood supply and tube called the ureter (which leads to the bladder)

2. Ureter carries urine from kidney to the bladder

3. Urine is excreted through the urethra of the penis/vagina.

2.68b Osmoregulation

Understand how the kidney carries out its roles of excretion and of osmoregulation 

1. (process) osmoregulation
Osmo = Osmosis
Regulation = to control

2. The tissue fluid which surrounds these cells must be ISOTONIC with the cytoplams of these cells (= the amount of water going into + out must be equal and the cells remain theier function + shape)

3. Blood circulating into the tissueHypertonic (conc) - add too much water to the cells
 Hypnotic (dilute) - remove too much water from the cells

4. ISOTONIC conditions is achieved by controlling the composition of blood
- blood forms the tissue fluid
- kidney controls the composition of blood
- excess water + salts are removed

2.68a Excretion

Understand how the kidney carries out its roles of excretion and of osmoregulation 

1. Excretion of Urea -> nitrogen (toxic) excess amino acids

- Blood circulates to the liver and the amino acids are broken down into the molecules --> Urea.
-Urea then circulates to the kidneys
- The kidneys filter the Urea from the blood 
- Urea is added to water --> Urine
- Urine is then collected in the bladder
-Urea is now in the bladder and removed from the body

2.67b Human organs of Excretion

Recall that the lungs, kidneys and skin are organs of excretion 
1. Lungs excrete carbon dioxide
2. Kidneys excrete excess water + urea (nitrogen wastes from amino acides) + salts
3. Skin excrete water + salts (sweat)

OBJ - 2.67a Excretion in plants

Recall the origan of carbon dioxide and oxygen as waste products of metabolism and their loss from the stomata of a leaf 

1. Example of Excretion (in leaf)
Carbon dioxide + Water --> Glucose + Oxygen (Waste molecule)
                                             Release of metabolic waste ^^

2. (Aerobic) Respiration
Glucose + Oxygen --> ATP + Carbon Dioxide + Water
                                                 Release of metabolic waste ^^

Friday, October 7, 2011

3.34 Causes of mutation

Understand that the incidence of mutations can be increased by exposure to ionizing radiation (for example gamma rays, X-rays and ultraviolet rays) and some chemical mutagens (for example chemicals in tobacco).

1. Mutation is the change in the base sequence of the gene.   New alleles are produced
2. what causes mutation?
examples are: a) radiation: X-rays, UV-B rays (sunshine) can cause skin cancer
                      b) chemicals such as tar - they are called mutagenes and cause cancer - carcinogens

3.33 Antibiotic resistance

Understand how resistance to antibiotics can increase in bacterial populations. 

1. Staphylococcus aureus ---> causes skin infections + lung infections

2. Infections can be treated with methecilline (antibiotic) it kills the Staphylococcus aureus. This is the susceptible form. MSSA.

3. Staphylococcus aureus infection increase is  caused by random mutation and when the methecilline (antibiotic) is applied - the bacteria does not die - this is called the resistant form. MRSA
The mutation has created genes in Staphylococcus aureus  that makes it resistant so it doesn't die from the methecilline (antibiotic).

4. Commonly found in hospitals - from treatment of people with wounds. Resulting in the methecilline (antibiotic) no longer working. 

3.32 Types of mutation

Understand that many mutations are harmful but some are neutral and a few are beneficial. 

1. Impact of mutation on new alleles. 

Process of mutation -->

Beneficial effect - eg: improve efficiency of an enzyme
Neutral effect - eg: ( no particular thing) but with time due to environmental change - can effect it.
Harmful effect - eg: mutation produces production of n enzyme that doesn't work.

Thursday, October 6, 2011

Obj - 3.31 Evolution

Describe the process of evolution by means of natural selection 

1. Evolution : a) change in the form of organisms - b) change in frequency of alleles. 
2. Natural slelection: is the system of evolution. (introduced by Charles Darwin)
3. Change in allele frequency by natural selection:
example: Staphylococcus aueurs.
*Susceptible: likely to be harmed by 
 2 features of classic process of  natural selection 
1. Random mutation - produces the MRSA resistant form
2. Non-random selection - due to the antibiotic which is selecting the MRSA (methecilline antibiotic) survive and the MSSA to be selected and killed.

3.30 Mutation

Recall that mutation is a rare, random change in genetic material that can be inherited. 
*Allele = form of gene

A change occurs which produces a new version of an allele which produces a different portion.
And resulting a different effect on the phenotype.

Different allele's exist due to mutation
Mutation - changes the base sequence of the gene.

3.29 Species Variation

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

1. variation = difference we can see in the phenotype (how things appear)
it is possible to count and measure these differences in graphic form.

An individual has a phenotype --> genotype --> which is modified by the environment.

variation pop = variation genotype = variation environment

Differences in the appearance of individuals in a species population  is because those individual have different genotypes and are living+surviving in different environments.

Graph "1" - suggests variation in the pop (species) is due to the variation in genotypes. (environment is normal here)
Discontinuous variation --->

Graph "2" suggests variation in the pop and variation in species.
The variation here is caused by genetic variation in the genotype

eg: Height in humans (affected by your diet)
Combo of genes + the environment.

these groups are modified by the environment which results in a smooth curve.

3rd case: Variation in a population (phenotypic variation) is due to environmental variation. The genes have no role to play in differences in pop.

eg: the home language you speak.