2.75 Urine

2.74 ADH.

2.73 Glucose re-absorption

2.71 Ultrafiltration

2.72 Water re-absorption

2.70 Nephron Structure

2.69 Urinary System

2.68b Osmoregulation

2.68a Excretion

2.67b Human organs of Excretion

2.67a Excretion in plants

3.34 Causes of Mutation

3.33 Antibiotic Resistance

3.32 Types of Mutation

3.31 Evolution

3.30 Mutation

3.29 Species Variation

3.21b Genetic Probabilities

3.21a Genetic Probabilities

3.20b Pedigree 2

3.20a

3.18c Codominance

3.19b F1 x F1 Cross

3.19a P1 x P1 Cross

3.18b Genotypes

3.18a Phenotypes

2.2-2.4 Cells

3 9b Female Reproductive System

3 9b Female Reproductive System

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

3.9a Male reproductive system

3.9a Male reproductive system

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

3.11 Placenta

3.11 Placenta

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

3.12 Amniotic fluid

3.12 Amniotic fluid

Understand how the developing embryo is protected by amniotic fluid

Surrounding the space of the embryo in the uterus is a fluid known as the amniotic fluid.

Its main function is to protect the embryo from any damage; the fluid also supports the foetus as it cannot bear its own weight as their bones are not calcified (hard)

The amniotic fluid is mostly made up of water which cannot be compressed. If the uterus experiences any blows or forces (e.g. the mother hits something), it will absorb the pressure and prevents any damage to the unborn child (acts like a shock absorber).

For example to experience this, one can be in a swimming pool and try to kick their foot out. They will see that their foot moves slightly slower, and it is harder to move.

3.24c Mitosis

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

3.24b Mitosis

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

3.24a Mitosis

 

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

3.16 DNA and Genetic information

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 thymine (T), and cytosine (C) with guanine (G)

Why are the two sections known as the 'sugar phosphate backbone?

3.15 Genes

Why is the genetic information transformed into protein?

3.14 Chromosomes

3.14 Chromosomes

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

Chromosomes are the genetic information within a cell. Within the nucleus a number of chromosomes would be found.

A chromosome is composed of a molecule DNA. This forms the shape known as the double helix.

Sections of the molecule are called Genes.

One chromosome will have thousands of genes carrying information for the construction of a protein.

Protein gives the characteristic associated with the gene such as a blood group.

A gene controls the production of protein which then controls the characteristic.

Different organisms have different amounts of chromosomes (per cell) :

Cat - 38

Chicken - 78

Chimpanzee - 42

Humans - 46

Chromosomes operate in pairs known as homologous pairs

The homologous nature is based on the length of a chromosome

How many homologous pairs are there in a human?

3.1 Sexual and Asexual Reproduction

3.1 Sexual and Asexual Reproduction

Describe the differences between sexual and asexual reproduction

What are chromosomes?

4.9 Carbon Cycle

4.9 Carbon Cycle

Describe the stages in the carbon cycle, including respiration, photosynthesis, decomposition and combustion

1) Photosynthesis -

Carbon dioxide comes from the atmosphere (0.03%)

When photosynthesis occurs it reduces the atmospheric Carbon dioxide

2) Feeding - Producer - Primary consumer (takes in carbon from the producer and reconstitute body material for growth) - Secondary consumer (carbon passes along the food chain). All levels in the food chain respire emitting carbon dioxide into the atmosphere.

3) Respiration - (for each stage in the food chain, each organism carries out the process of respiration)

(Begins with organic molecules; glucose). The process releases energy which is used for growth and movement. It also produces Carbon dioxide and water. Respiration adds carbon dioxide to the atmosphere.

4) Decomposition - All of the organisms in the food chain eventually die. The organic molecules are broken down by decomposer organisms known as bacteria and fungi. This causes the release of Carbon dioxide into the atmosphere as well.

5) Combustion -

1. Fossil fuels (formed millions of years ago due to the compression of plants and animals forming coal, oil and natural gas) are combusted to produce carbon dioxide. E.g. Industrial/motor (cars, aeroplanes, Lorries all combust fuels)

2. Environment- lightning striking vegetation causing forest fires causing carbon dioxide to get released into the atmosphere 

4.14 Enhanced Greenhouse effect

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

Enhanced Greenhouse effect:

Pollution - molecules such as water vapour, carbon dioxide and methane (greenhouse gases) increase their concentration in the upper atmosphere.

As a result the infrared light would re-emit towards the surface of the Earth rather than it being released back out into space.

This raises the average global temperature which is known as global warming

Consequences:

-melting of ice caps in polar ice caps

-deserts would expand

-raised sea levels

-change of ocean currents

-winds

-coniferous forest's distribution would alter

These all contribute to the main factor of climate change.  There would be changes in the world's distribution of Biomes- major vegetation ecosystems.

4.12 Greenhouse effect

4.12 Greenhouse effect

Recall the water vapour, carbon dioxide, nitrous oxide and CFC's are greenhouse gases

4.13 Greenhouse gases

4.13 Greenhouse gases

Understand how human activities contribute to green house gases

Fossil Fuels:

1) Industrial (factories)

2) Cars

3) Domestic

The burning of fossil fuels causes the release of Carbon dioxide, nitrous dioxide and sulphur dioxide. These are known as greenhouse gases. These gases in upper atmosphere absorb infrared light and redistribute the gases to the surface of the planet.

Farming- Animals (cows) when digesting crops emit Methane gas into the atmosphere. It is a significant contributor to the greenhouse gases- almost 9%

Evaporation of water- forms water vapour- clouds are also adds to greenhouse gases

Refrigeration/solvents/propellants- known as chlorofluorocarbons (CFC's).  A combination of Chlorine, Carbon, and Fluorine (Cl₃F)

4.11 Gas pollution

4.11 Gas pollution

Understand the biological consequences of pollution of air by sulphur dioxide and by carbon monoxide

1)      Sulphur dioxide – SO₂

The gas is added to the atmosphere when the combustion of fossil fuels (coal, oil and natural gas) occur in factories. (Sulphur dioxide is also produced from vehicles)

In the atmosphere Sulphur Dioxide combines with water vapour to produce Sulphuric Acid.

Sulphuric acid is found within water (in clouds) and when it rains it is known as acid rain.

Effects of Sulphur dioxide:

-Animals (the aluminium ions have an effect on fish; it thickens the mucus that lines the gills and reduces the fishes intake of oxygen from the water. The fish in turn suffocates and eventually dies.

-Lakes (the rain will forms streams, which will grow to form lakes. Acid rain reduces pH (make them acidic) and releases aluminium ions.

-Forests (trees and plants are 'burned' by the acid rain)(root system- Sulphuric acid causes the calcium and magnesium ions (Ca2+ and Mg2+) to be leeched out of the soil. The plant cannot obtain either magnesium or calcium; therefore yellowing of leaves occurs/the plant cannot grow.

2) Carbon Monoxide

It is produced when fossil fuels (especially gases) are burned with insufficient oxygen. CO combines with the hemoglobin in the red blood cells and forms a molecule called Carbonmino hemoglobin. It blocks the hemoglobin from carrying oxygen.

Effects of CO:

-Reduces oxygen circulation

- Toxic

- Too much of it can cause death

- It is very difficult to separate the Carbon monoxide molecule from the hemoglobin

4.7 Energy efficiency

4.7 Energy efficiency

Explain why only about 10% of energy is transferred from one tropic level to the next.

4.6 Energy and substances in food chains

Understand the transfer of substances and of energy along a food chain

4.6 Energy and substances in food chains

Understand the transfer of substances and of energy along a food chain

Bush grass (producer) - Impala (primary consumer) - leopard (secondary consumer) - if ever eaten by lion (tertiary consumer)

Producer - converts light energy into chemical energy. Chemical energy takes form of organic molecules including carbohydrates, proteins, and lipids. (Food to impala, leopard, and lion). These molecules are composed of:

C-H

C-O

C-C

O-H

C-N

All these bonds represent energy. (Carbon, hydrogen, oxygen and nitrogen are substances/matter)

As the bush grass photosynthesises, it creates organic molecules which are the substances which contain energy that came from sunlight. The impala consumes this for growth, respiration, and life processes. The cheetah then eats it and then processes these molecules by reorganising it.

Each stage of the food chain contains the substances of matter and energy (bonds between elements)

4.5b Food Webs

4.5b Food Webs

Understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer

The food web enables us to provide a better description of the ecosystem.

Ecosystem is a community of organisms which are interacting, in this example they are FEEDING

An Advantage is that it allows us to see organisms feeding at different trophic levels. However its consequences are that:

1) Organisms can have multiple predators

2) Organism may feed on multiple preys

3) Results in food chain becoming linked

You can see that the Hawk can either be the secondary or tertiary consumer.  It is a multiple predator

The slug is the prey to badgers, small birds and hedgehogs

The fox feeds on the rabbit, mice and shrew. This causes it to become linked.

Some food chains have 2 or 3 links to them.