4.11 understand the biological consequences of pollution of air by sulfur dioxide and by carbon monoxide

carbon monoxide - greenhouse gas

sulfur dioxide - acid rain

3.8 describe the structure and explain the function of the male and female reproductive systems

Male
Testis - produce sperm cells
Sperm duct (vas difference) - carries sperm to the penis
The prostate gland - adds fluid to the sperm, creating semen
The urethra - carries sperm out of the penis.

Female
Ovaries - produce eggs
Oviduct (fallopian tube) - carry the eggs to the uterus, is the site of fertilisation
Uterus - develops the fertilised egg on the placenta

2.83 describe how responses can be controlled by nervous or by hormonal communication and understand the differences between the two systems

nervous system - electrical impulses
hormones - chemicals

(nervous is much faster than hormonal)

1.2 describe the common features shared by organisms within the following main groups: plants, animals, fungi, bacteria, protoctists and viruses, and for each group describe examples and their features as follows (details of life cycle and economic importance are not required)

Plants
- Are multicellular organisms
- their cells contain chloroplasts
- have cell walls made of cellulose
- they sort carbohydrates as starch or sucrose
-have a nucleus
- they can photosynthesise

Animals
- are multicellular organisms
- cells do not contain chloroplasts
- have no cell walls
-store carbohydrates as glycogen
- have a nucleus

Fungi
- some are multicellular, some are single celled
-have cell walls made of chitin
- store carbohydrates as glycogen
- their body is organised into a mycelium made from thread-like structures called hyphae which may contain nuclei
- can not carry out photosynthesis (and therefore do not contain chloroplasts). Instead they feed by saprotrophic nutrition (extracellular secretion of digestive enzymes onto food material and absorption of the organic product


Bacteria
- all are single celled
-have a cell wall
- lack a nucleus but contain a circular chromosome of DNA (a plasmid)
- some can carry out photosynthesis, must most feed of living or dead organisms

Protoctists
- all are single celled
- some have chloroplasts (but some don't)
- some have features like animals (for example, no cell wall) whilst others have features like plants (for example, have a cell wall)

Viruses
- they have no cellular structure (so are not even single celled)
- they have a protein coat
- they contain one type of nucleic acid (either DNA or RNA)
- can not photosynthesise. They are parasitic and can reproduce only inside living cells. They infect every type of living organism.

Examples

Plants - maize
animal - human
fungi - Mucor (multicelled), yeast (single celled)
bacteria - lactobacillus
protoctists - amoeba (plant like) chlorella (animal like)
viruses - influenza, HIV

Quick notice

Hi all!

Hope all your revision is going well, I have now finished the spec for biology and am going through each point, editing and correcting any mistakes/typos I have made/you have pointed out (and also learning the points for myself!).

If there are any mistakes I've failed to spot/anything I have got wrong/anything you don't understand please don't hesitate to comment & I will amend as soon as possible :)

Hope all your exams go well,

Millie

2.16 describe experiments to investigate diffusion and osmosis using living and non-living systems.

Diffusion in non-living
- Make agar jelly by mixing phenolphthalein and dilute sodium hydroxide (NOTE: The jelly will be pink from the phenolphthalein, incase you were wondering)
- Fill a beaker with dilute hydrochloride acid
- Cut different sized cubes (e.g 1x1cm, 2x2cm, 3x3cm) and put them in the dilute hydrochloric acid
- Leave the cubes for a whole

you should observe that they go colourless because the acid diffuses into the agar jelly


Osmosis in living
- cut a potato into 5 even cuboids, measure their lengths
- obtain 4 beakers wit different sugar solutions in them, and 1 with just watr (this will be our control)
- put each potato strip into one of the 5 beakers
- leave for 1 hour
- remove potato and measure strips again

Conclusion - if water has entered the potato, the length will be greater, if it has left, the length will be shorter (than before).


Osmosis in non-living

- tie a piece of string/wire around one end of some visking tubing and put a glass tube in the other, fixing it in place with more wire.
- pour sugar solution down the glass tube into the visking tubeing
- put the visking tubing into a beaker, fill the beaker with pure water and make a note of how far up the beaker the waterline sits
- leave the experiment overnight
- return the next day and measure the amount of water in the beaker

Conclusion - the water should have been drawn into the Visking tubing by osmosis, this will force the liquid up the glass tube

3.33 undersand that the incidence of mutations can be increased by exposure to ionising radiation (for exampe gamma raysX-rays and ultraviolet rays) and some chemical mutagens (for example chmicals in tobacco)

Ionising radiation can induce mutations. So can some chemicals in tobacco as
this is why you can get cancer from smoking (as some cancers are a mutation of a cell)

5.20 evaluate the potential for using cloned transgenic animals, for example to produce commercial quantities of human antibodies or organs for transplantation

When evaluating, you just need to go over the positives and negatives and weigh up which is more (more positives or more negatives)

Positives

- Animals can produce medicines in their milk. Human genes can be transferred into animals to produce human antibodies to fight illnesses such as arthritis, multiple sclerosis and some types of cancer.

- Animals have organs suitable for transplant into humans (e.g. pigs). They could be developed by genetic engineering then cloned.

- Farmers do not have to wait for a 'good animal' like with normal breeding, all their animals could be beneficial with cloning

Negatives

- Cloned animals MAY not be as healthy as normal animals

- Lots of mistakes; embryos from cloned animals often do not develop well/efficiently/normally

- It is difficult, expensive and time consuming

- There may be long term risks that we are unaware of

5.19 describe the stages in the production of cloned mammals involving the introduction of a diploid nucleus from a mature cell into an enucleated egg cell, illustrated by Dolly the sheep

Dolly is just used as an example as she was the first cloned mammal. The method is as follows...


- Remove the nucleus of an egg cell. This creates an enucleated egg cell (just a cell without a nucleus)

- Insert the nucleus of a diploid cell of the mammal you want to clone

- shock the new cell by electric shock to start division by mitosis. This creates an embryo

- Implant the embryo into the uterus of a surrogate mother (has to be the same species) to develop.

Now wait for the animal to be born

5.18 understand how micropropogation can be used to produce commercial quantities of identical plants (clones) with desirable characteristics

If loads of plants are required, you can take cuttings from the explants to produce even more plants. It is also very quick so the farmer will not need to rely on the correct conditions like during natural growth - the commercial company can ensure they ill have stock (of plants).

NOTE: the process of micropropogation is explained in point 5.17.

5.17 describe the process of micropropogation (tissue culture) in which small pieces of plants (explants) are grown in vitro using nutrient media

Micropropogation is a technique used to clone plants. Here's how it works...

- A plant with desired characteristics is selected to be cloned. Small pieces are cut from the tips of the stems and the side shoots of the plant (these cuttings are known as explants)

- The explants are sterilized to kill any microorganisms

- The explants are grown in vitro. All this means is that they're placed in a petri dish that contains a nutrient medium. This medium has all the stuff the plant needs to grow. It also contains growth hormones (auxins)

- The explant begins to grow and are taken out of the medium and planted in soil.


These plants develop into plants that are genetically identical to the original plant, meaning they will share the same characteristics.

5.16 understand that the term 'transgenic' means the transfer of genetic material from one species to a different species

Transgenic means the transfer of genetic material from one species to another. If something is said to be transgenic, it means  they contain  genes transferred from another species.

5.15 evaluate the potential for using genetically modified plants to improve food production (illustrated by plants with improved resistance to pests)

Crops can be genetically modified to increase yield. For example, making them resistant to insects/weed killers.

Making them insect resistant means farmers can spend less money on chemicals such as pesticides, this also increases yield.

making them resistant to weedkiller means farmers can kill weeds without killing the plant.

However, many people are against genetically modifying foods as there are no studies on long term effects on humans. There are also religious reasons. Also, if a weed gets the weedkiller resistance gene, there will be no way to kill it.

5.14 understand that large amounts of human insulin can be manufactured from genetically modified bacteria that are grown in a fermenter

This is one of the uses of genetic engineering, here's how it works...

- the DNA you want to insert (in this case, the gene for human insulin) is cut out of a human cell using a restricton enzyme.

- The vector DNA (either a plasmid or virus, in this case, plasmid) is cut open with a restriction enzyme.

- the vector DNA and insulin DNA are combined with a mixture of ligase enzymes. The ligase enzymes join the two pieces of DNA together, producing recombinant DNA

- The recombinant DNA is inserted into  a bacterium

- The bacterium is grown in a fermenter


The bacteria cells now make insulin. This is useful to produce insulin on a mass scale for people with diabeties etc.

5.13 describe how plasmids and viruses can act as vectors, whch take up pieces of DNA, then insert this recombinant DNA into other cells

A vector is something that is used to transfer DNA into a cell. The two types of vectors are plasmids and viruses.

Plasmids - small circular molecules of DNA that can be transferred between bacteria

Viruses - insert DNA into the organisms they infect

5.12 describe the use of restriction enzyme to cut DNA at specific sites and ligase enzyme to join pieces of DNA together

Ligase enzymes are used to join together two pieces/strands of DNA, alternatively, the restriction enzyme cuts DNA at a specific point by recognizing the specific sequences of DNA.

NOTE: Two different bits of DNA that have been stuck together is known as recombinant DNA

5.11 understand that animals with desired characteristics can be develope by selevtive breeding

Selective breeding can ensure an animal produces the maximum yield of, for example, meat/milk, has good health/disease resistance, has good mothering skills, not a bad temper, is fast (good for racehorses etc) and has high fertility.

5.10 understand that plants with desired characteristics can be developed by selective breeding

Selective breeding can be used to combine the best characteristics to produce the best crops.

For example, tall wheat plants have a very good yield but are easily damaged by the elements whereas dwarf wheat plants can resist the elements but have quite a low yield. The two plants can be bred together, ensuring the offspring can battle the elements and have a good crop yield.

5.9 explain the methods which are used to farm large numbers of fish to provide a source of protein, including maintenance of water quality, control of intraspecific and interspecific predation, control of disease, removal of waster products, quality and frequency of feeding and the use of selective breeding

Fish farming is a possible solution to the problem of overfishing. It is controlled and designed in a way to produce as many fish as possible.

NOTE: Everything specifically to do with fish farming in cages in the sea is in blue, everything specifically to do with fish farming in tanks is in green.

Maintenance of water quality
There is a current in the sea so water is naturally kept 'clean'.
The water can be removed, filtered and cleaned. Water can be monitored to ensure temperature, [H and oxygen level is at the best potential.

Control of intraspecific and interspecific predation

Firstly, interspecific predation is being eaten by other animals, intraspecific predation is cannibalism, basically.

Fish farming in cages stops interspecific predation as it means no animals/fish can eat the farmed fish. Big fish and baby fish are kept separate to keep intraspecific predation low.

Control of disease

Fish in cages are prone to diseases such as lice . Biological pest controls are used to control the lice as chemical pesticides can harm the fish.

Removal of waste products

The water can be removed and filtered, getting rid of waste.

Quality and frequency of feeding

A diet of food pellets is carefully controlled to maximize the amount of energy the fish get as more energy = more growth = bigger fish. Furthermore, the better the quality of food, the bigger the fish will grow.

It is easy to control how much food is given, as it doesn't wash away in the current of the sea.

Selective breeding

The fish can be selectively bred to produce fast growing, less aggressive fish, for example.

5.8 interpret and label a diagram of an industrial fermenter and explain the need to provide suitable conditions in the fermenter, including aseptic precautions, nutrients, optimum temperature and pH, oxygenation and agitation, for the growth of micro-organisms

Okay so to start, here is a diagram...

Conditions...

The fermenter must be kept aseptic so only the desired microorganism grows. In order to do this, it is cleansed (usually with steam) before production takes place.

Nutrients are provided to ensure that the microorganisms always have enough food to grow.

The optimum temperature and pH is maintained and monitored with probes (connected to a screen)  to ensure maximum growth. Also, if the temperature is too high, the enzymes will denature. An optimum temperature needs to be kept to ensure the best yield.

If the process requires aerobic respiration (not beer, for example, which requires anaerobic respiration of yeast to make ethanol), there is an oxygen supply.

Agitation/stirring takes place to ensure that the microorganisms, nutrients and temperature are evenly distributed.

image credit: BBC