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82 Cards in this Set

  • Front
  • Back

What's meant by biodiversity?

The variety of living organisms in an area

What's meant by species?

A group of similar organisms able to reproduce to give fertile offspring

What's meant by habitat?

The area inhabited by a species. Includes physical factors (like soil, temperature range) and the living (biotic) factors (like food availability, presense of predators)

Why is biodiversity important?

- essential in maintaining a balanced ecosystem for all organisms


- all species are interconnected - they depend on one another

What is habitat biodiversity?

It refers to the number of different habitats found within an area. Each habitat can support a number of different species. For example a particular area could contain many different habitats like sand dunes, woodland, meadows, streams etc.

What are the two components that make up species biodiversity?

Species richness - the number of different species living in a particular area.


Species evenness - a comparison of the numbers of individuals of each species living in a community.

What is meant by community?

Refers to all the populations of living organisms in a particular habitat.

What is meant by genetic biodiversity?

Refers to the variety of alleles within a species (or a population of species).

What are rhizomes?

Rhizomes are stem structures that grow horizontally underground away from the parent plant. They have 'nodes' from which new shoots and roots can develop.

What are stolons? (also called runners)

Stolons are similar to rhizomes. The main difference that they grow on the surface of the soil. New shoots and roots can either develop from nodes or form at the end of the stolon.

What are suckers?

Suckers are shoots that grow from undeveloped shoots present on the shallow roots of a parent plant.

What are tubers?

Tubers are large underground plant structures that act as a food store for the plant. They're covered in 'eyes'. Each eye is able to sprout and form a new plant.

What are bulbs?

Bulbs are underground food stores used by some plants. New bulbs can develop from the original bulb and form new individual plants.

Example of rhizomes?

Bamboo

Example of stolons/runners?

Strawberries

Example of suckers?

Elm trees

Example of tubers?

Potatoes

Example of bulbs?

Onions

Micropropagation is often used to produce plants when the desirable plant...

- does not readily produce seeds


- doesn't respond well to natural cloning


- is very rare


- has been genetically modified or selectively bred with difficulty


- is required to be 'pathogen-free' by growers e.g. strawberries

Plants can be artificially cloned by tissue culture. How is it usually carried out?

1. Cells taken from original plant that will be cloned


2. Cells from stem, root tips are used as they're stem cells.


3. Cells are sterilised to kill microorganisms - bacteria + fungi compete for nutrients w plant cells, which decreases their growth rate


4. Cells placed on culture medium containing plant nutrients and growth hormones


5. When the cells have divided and grown into a small plant, they're taken out + planted in soil - will develop into plants that are genetically identical to the original.

What is micropropagation?

The process of making large numbers of genetically identical offspring from a single parent plant using tissue culture techniques.

Arguments for micropropagation

- allows for rapid production of large numbers of plants w known genetic make-up which will yield good crops


- produces disease-free plants


- possible to produce viable no. of plants after GM of plant cells


- provides way of producing v large no. of new seedless plants + sterile enough to meet consumer tastes


- provides way of growing plants that are relatively infertile/difficult to grow from seed


- can reliably increase no. of rare/endangered plants.

More arguments for tissue culture

- desirable genetic characteristics always passed onto clones. Doesn't always happen when plants reproduce sexually


- allows plants to be reproduced in any season as environment is controlled


- less space required by tissue culture


- produces lots of plants quickly compared to growing them from seeds

Arguments against micropropagation

- produces monoculture so genetically identical plants are all susceptible to same diseases or changes in growing conditions


- v high production costs due to high energy use + requires skilled workers so unsuitable for small-scare production


- contamination by microorganisms during tissue culture can be disastrous and result in complete loss of plants being cultured.

How can animal clones occur naturally?

During sexual reproduction, a fertilised egg coild split during v early stages of development + develop into multiple embryos w same genetic info. Embryos can develop as normal to produce offspring that are all genetically identical (clones). E.g. identical twins are clones.

Artificial embryo twinning (similar to when animal clones form naturally) - example for cows

1. Egg cell extracted from female cow + fertilised in petri dish


2. Fertilised egg is left to divide at least once, forming an embryo in vitro (outside living organism)


3. Individual cells from embryo are separated + each is put into separate petri dish. Each cell divides + develops normally so an embryo forms in each petri dish.


4. Embryos then implanted into female cows (surrogate mothers)


5. Embryos develop into surrogates, eventually offspring are born. All genetically identical to eachother.

Somatic Cell Nuclear Transfer (SCNT) - example for sheep

1. A somatic cell (any non-reproductive cell) is taken from sheep A. Nucleus is extracted + kept


2. An oocyte (immature egg cell) taken from sheep B. Its nucleus is removed to form an enucleated oocyte


3. Nucleus from sheep A inserted into enucleated oocyte - oocyte from sheep B now contains genetic info from sheep A


4. Nucleus + enucleated oocyte are fused together + stimulated to divide (by electrofusion). Produces an embryo.


5. Embryo implanted into surrogate mother, eventually lamb is born that's a clone of sheep A

What can animal cloning be used for?

- research purposes e.g. new drugs. All genetically identical so variables from genetic differences are removed


- to save endangered animals from extinction


- in agriculture, farmers can increase no. of animals with desirable characteristics


- to genetically modify animals to produce a useful substance


- replace damaged tissue with embryonic stem cells

Immobilised enzymes can be used to convert lactose to glucose and galactose

Some people are lactose-intolerant as they don't produce lactase to break lactose down into glucose + galactose (via hydrolysis).


Fresh milk can be passed over immobilised lactase to produce lactose-free milk

Immobilised enzymes can help production of semi-synthetic pencillins

Some bacteria are pencillin-resistant. Semi-synthetic pencillins now produced w the same antibiotic properties as natural pencillin but are effective against pencillin-resistant organisms. Immobilised pencillin acylase enzyme used.

Immobilised enzymes can convert dextrins into glucose

Glucose + glucose syrup used in large amounts in industry (e.g. thicken and sweeten food)


Glucose can be derived from starchy food w immobilised enzymes


Starch breaks down into dextrins which are then broken down into glucose w the immobilised enzyme glucoamylade.

Immobilised enzymes can convert glucose to fructose

Fructose used as sweetener - using this instead of glucose means there's less sugsr in our foods that needed to obtain the same level of sweetness


Immobilised glucose isomerase used on industrial scale

Immobilised enzymes can produce pure samples of L-amino acids

Amino acids have 2 chemical isomers - L or D. Body utilises L form.


Scientists chemically synthesise amino acids + end up w mixture. Immobilised aminoacylase separates, used in industrial scale


Can be used for making animal + human food including dietary supplements

Immobilised enzymes can convert acrylonitrile to acrylamide

Acrylamide used in industry for synthetic polymers e.g. plastics w wide range of uses


In industry, immobilised nitrilase used to convert acylonitrile to acrylamide

What's a gene?

A sequence of bases on a DNA molecule that codes for a protein (polypeptide), which results in a characteristic.

What's an allele?

A different version of a gene.

What's meant by genotype?

The alleles an organism has

What's meant by phenotype?

The characteristics the alleles produce

What's meant by dominant?

An allele whose characteristic appears in the phenotype even when there's only one copy. Dominant alleles are shown by a capital letter.

What's meant by recessive?

An allele whose characteristic only appears in the phenotype if two copies are present. Recessive alleles are shown by a lower case letter.

What's meant by codominant?

Alleles that are both expressed in the phenotype - neither one is recessive.

What's meant by locus?

The fixed position of a gene on a chromosome. Alleles of a gene are found at the same locus on each chromosome in a pair.

What's meant by homozygote?

An organism that carries two copies of the same allele.

What's meant by heterozygote?

An organism that carries two different alleles.

What's meant by carrier?

A person carrying an allele which is not expressed in the phenotype but that can be passed on to offspring.

Transcription factors control gene expression at the transcriptional level. What's meant by transcription factors?

Proteins that bind to DNA and switch genes on or off by increasing or decreasing the rate of transcription. Factors that increase the rate are called activators and those that decrease the rate are called repressors.

Where do transcription factors bind to in prokaryotes and eukaryotes?

In eukaryotes, transcription factors bind to specific DNA sites near the start of their target genes.


In prokaryotes, transcription factors bind to operons.

What's an operon?

A section of DNA that contains a cluster of structural genes, that are transcribed together, as well as control elements and sometimes a regulatory gene.

What do structural genes code for?

Useful proteins, such as enzymes

What do control elements consist of?

They include a promoter (a DNA sequence located before the structural genes that RNA polymerase binds to) and an operator (a DNA sequenve that transcription factors bind to).

What do regulatory genes code for?

An activator or repressor

What is E.coli?

A bacterium that respires glucose, but can use lactose if glucose is unavailable

What genes are found on the lac operon?

The genes that produce the enzymes needed to respire lactose

What happens if lactose is not present?

The regulatory gene produces the lac repressor, which is a transcription factor that binds to the operator site when there's no lactose present. This blocks transcription as RNA polymerase can't bind to the promoter.

What happens when lactose is present?

It binds to the repressor, changing the repressor's shape so it can no longer bind to the operator site.


RNA polymerase can now begin transcription of the structural genes.

What are the three structural genes in the lac operon?

lacZ, lacY and lacA, which produce proteins that help the bacteria digest lactose (including B-galactosidase and lactose permease)

What are introns?

Sections of DNA that don't code for amino acids

What are exons?

Sections of DNA that do code for amino acids

What's meant by pre-mRNA?

During transcription, the introns and exons are both copied into mRNA. mRNA strands containing introns and exons are called primary mRNA transcripts (pre-mRNA)

What is splicing?

A process in which introns are removed from primary mRNA strands. Introns are removed and exons are joined, forming mature mRNA strands. This occurs in the nucleus. Mature mRNA then leaves the nucleus for translation.

What are hox genes?

The proteins that control body plan development are coded for by Hox genes.

What's a homeobox sequence?

Hox genes have regions called homeobox sequences, which are highly conserved - this means these sequences have changed very little during the evolution of different organisms that possess these homeobox sequences.

How do Hox genes control development?

- homeobox sequences code for a part of the protein called the homeodomain


- the homeodomain binds to specific sites on DNA, enabling the protein to work as a transcription factor


- the proteins bind to DNA at the start of developmental genes, activating or repressing transcription and so altering the production of proteins involved in the development of body plans

What are the features of the kingdom prokaryotae?

Prokaryotic, unicellular, no nucleus, less than 5 micrometres

What are features of the kingdom protoctista?

Eukaryotic cells, usually live in water, single-celled or simple multicellular organisms

What are features of the kingdom fungi?

Eukaryotic, chitin cell wall, saprotrophic (absorb substances from dead or decaying organisms), single-celled or multicellular organisms

What are features of the kingdom plantae?

Eukaryotic, multicellular, cellulose cell walls, can photosynthesise, contain chlorophyll, autotrophic (produces their own food)

What are features of the kingdom animalia?

Eukaryotic, multicellular, no cell walls, heterotrophic (consume plants and animals)

The binomial naming system is used in classification

All organisms given one internationally accepted scientific name in Latin that has 2 parts:


First is genus name, has a capital letter.


Second is species name, begins with lower case letter.


Names always written in italics (or underlined if handwritten)

What's phylogeny?

The study of the evolutionary history of groups of organisms. Phylogeny tells us who's related to whom and how closely related they are.

Diseases caused by bacterium

- Tuberculosis (TB) - M.bovis and Mycobacterium tuberculosis, affects animals and typically humans + cattle


- Bacterial meningitis - affects humans


- Ring rot - Clavibacter michiganesis affects potatoes, tomatoes

Diseases caused by viruses

HIV/AIDS - affects humans


Influenza - affects animals, including humans


Tobacco Mosaic Virus - affects plants

Diseases caused by fungus

Black sigatoka - affects banana plants


Ringworm - affects cattle


Athlete's foot - affects humans

Diseases caused by protoctist

Potato/tomato late blight - affects potatoes/tomatoes


Malaria - affects animals, including humans

Multiple copies of a DNA fragments can be made using PCR

1. Reaction mixture set up containing DNA sample, free nucleotides, primers and DNA polymerase


2. Mixture heated to 95°C to break H bonds between 2 DNA strands. DNA polymerase doesn't denature at this temperature.


3. Mixture cooled to 50-65°C so primers can bind to strands.


4. Mixture heated to 72°C so DNA polymerase can work


5. DNA polymerase lines up free DNA nucleotides alongside each template strand. Complementary base pairing means new complementary strands can be formed.


6. 2 new copies of fragment of DNA formed, one cycle of PCR complete.


7. Cycle starts again w mixture heated to 95°C + all 4 strands (2 original, 2 new) used as templates

Conservation

Conservation involves the management of ecosystems - controlling how resources are used and replaced. It can also involve reclamation - restoring ecosystems that have been damaged or destroyed so they can be used again.

Preservation

The protection of ecosystems so they're kept exactly as they are. Nothing is removed from a preserved ecosystem and they're only used for activities that don't damage them.

Coppicing

Cutting down trees in a way that lets them grow back so new trees don't need to be planted.

Why do native tree species tend to be planted in preference to non-native species?

It's better for biodiversity because native species have long-established interactions with other native species (e.g. plants, fungi, animals), so their presence should help species thrive in an area. Also some species might not adapt to the presence of non-native tree species.

Carrying capacity

The maximum stable population size of a species that an ecosystem can support

Positive ethical issues surrounding gene therapy

- could prolong the lives of people with genetic disorders


- could give people with genetic disorders a better quality of life


- carriers of genetic disorders might be able to conceive a baby without that disorder or risk of cancer (only in germ line therapy)


- it could decrease the number of people that suffer from genetic disorders (only in germ line therapy)

Negative ethical issues surrounding gene therapy

- technology could potentially be used in ways other than for medical treatment, eg. treating the cosmetic effects of ageing


- there's the potential to do more harm than good by using the technology (e.g. overexpression of genes)


- concern that gene therapy is expensive - some people think money is better spent on other treatments that have passed clinical trials