3.24

3.14

- Chromosomes: Genetic information within a cell

- Chromosomes are in the nucleus of a cell.

-Chromosomes: Is composed of a molecule called DNA. DNA forms a shape called the double helix. Sections of the molecule are called genes. One chromosome will have many jeans (possibly 1000).

- Each gene carries the info for the construction for a protein. The protein gives us the characteristic associated with the gene, (i.e blood group)

- Diff organisms have different number of chromosomes (cat 37, chicken 78, chimp 42, human 46)

- Chromosomes are known to operate in pairs, known as homologous pairs. Same Gene, in the same place on each chromosome in homologous pair. Same gene but different version

- Characteristic  2 versions of each. These versions are called Alleles

3.1 Sexual and Asexual reproduction

Sexual reproduction:
Show sex (genders – male/female)
Produce cells called gametes (male=sperm female=egg)
Meiosis- the type of cell division that produces gametes –effect: half the total number of chromosomes in the gamete cell (e.g. chromosomes. Humans: 46 per cell Gametes: 23 per cell, the process from going from 46 to 23 is called Meiosis.
Fertilisation (gametes cells from a male (sperm) fuse together with the gamete cell from a female (egg))
Broad variation (many differences in individuals of population)

Asexual reproduction:
DO NOT show sex (genders – male/female)
No gametes
Mitosis (in eukaryotic cells) /binary fission (in prokaryotic bacterial cells) cell with 20 chromosomes  2 cells (each with 20 chromosomes -identical)
No fertilisation (because no gametes)
Small variation – due to mutation (they are identical ‘clone’)


Quetion: What are eukaryotic cells and prokaryotic bacterial cells?

Obj 4.9

1.CO2 from Atmosphere. .03 of atmosphere
Photosynthesis – reducing the atmosphere CO2



2.Producers eaten by primary consumers.
PC takes in the carbon from the producer to put back together its own body materials (grows)
Primary Consumers eaten by secondary consumer..etc




3.Each organism carries out the process of respiration.
respiration adds CO2to the atmosphere.
All organisms are putting carbon into the atmosphere through respiration



4.Death of organisms
Organic molecules that remain are broken down by the decomposer organism (bacteria and fungi) results rerelease of CO2 back to atmosphere



5. Fossil fuel (compression and pressure of animals) results in formation of oils and coals. Which are combusted to release co2
e.g. 1. industrial/motor vehicle
2. Naturally: lightning striking vegetation – forest fires and grassland fires.

Obj 4.14

By Pollution
Molecules such as Carbon dioxide, methane and water vapour (greenhouse gasses). These gases will increase the concentration in the upper atmosphere. And the consequences are the infer red light from the planet surface would be readmitted constantly back to the surface (rather than escaping) this cause a raise in the average global temperature = Global warming.
Consequences
- Malting of ice caps
- Raise in sea levels
- Ocean currents change
- Change the way Wind generated
- Distribution of the world’s Biomes (‘Ecosystem’)
- Deserts expand

Obj 4.13

1. Human activities i.e burning of fossil fuels results in the formation of CO2/NO2/ SO2 (greenhouse gasses)
They absorb infer red light and they will redistribute it back towards the planet
Fossil fuels from factories (industrial) and vehicles and burning of coals (domestic)
2. Farming. –Cows admit ethane gas into atmosphere (Around 9% of greenhouse gasses)
3. Evaporation of water  water vapour (Clouds)
4. Refrigeration/ Solvents/ propellants.
CFC (Chlorine, Florine, Carbon) i.e CCL3F

Obj 4.12

obj 4.11

Sulphur dioxide ( SO2 – gas)

Combustion of fossil fuels in factories (ie coals and oils) gives off the gas SO2
Also in vehicle the combustion of oils/petrol/gas also contributes

In atmosphere SO2 +H2O -> sulphuric acid
Condenses to form clouds and when it rains we call this acid rain.
Acid rain affects plants and animals
Trees and plants are often ‘burned’ (tops of trees)
Acid rain causes Ca2+ and mag 2+ to be LEACHED out of soil (plant can’t obtain magnesium or calcium in plant which means the plant can’t grow)
Effect of acid rain in lakes (enters strems which then form lakes) reduce the pH which releases the Al3+ ions. Which affect the rate of fish deaths. The aluminum causes the thickening of the mucus which lines the sides of the fish’s gills, which reduces the fish ability to take oxygen from water = suffocation (death)

Carbon monoxide (CO)

Fossil fuels (coal/gas) are burned with insufficient oxygen which creates CO
Carbon monoxide (CO) combined with the hemoglobin which is formed in the Red Blood cells and forms a molecule called Carbamino hemoglobin (blocks hemoglobin from carrying O2, reduced 02 circulations.) Is Toxic = causes death