Using Biology Flashcards
How can awareness of limiting factors and how they affect the rate of photosynthesis be used by farmers?
To improve crop yields
When can’t a farmer control limiting factors?
If their crops are being grown outside
How does growing plants in an enclosed environment affect farmers and why?
It increases their crop yields as they can control the climate inside
Examples of enclosed environments for crops to grow
Glasshouses, polythene tunnels
Whatis the purpose of manipulating condiitons in a glasshouse?
To increase the rate of photosynthesis
How can conditions be manipulated in a glasshouse?
Artificial heating, artificial lighting, increasing carbon dioxide content, regular watering
How does artificial heating in glasshouses work?
Enzymes controlling photosynthesis can work faster at slightly higher temperatures
Where in the world can artificial heating be used?
In temperate countries such as the UK
How is artificial lighting useful in glasshouses?
It means that plants can synthesise for longer
How is increasing carbon dioxide content of the air inside a glasshouse useful?
It means that plants can photosynthesise quicker
What do farmers need to financially balance when using glasshouses?
The extra cost of providing manipulating conditions against increased income
Can tropical countries use glasshouses to control other conditions?
Yes as long as they are well ventilated to release hot air and avoid temperatures rising too high
What happens if temperatures rise too high in a glasshouse?
The enzymes controlling the photosynthesis reaction may denature
What are polythene tunnels (polytunnels)?
Large plastic tunnels that cover crops
What do polytunnels do?
Protects crops grown outside from the effects of weather, including excessive wind, rain and extreme temperatures
What can polytunnels do to the temperature inside the tunnel?
Increase it slightly
What can polytunnels prevent?
The entry of pests that can damage plants or diseases that can kill plants
What is a limiting factor?
A factor that is the lowest at the time that limits something from occurring to its full potential
What are the three main factors that limit the rate of photosynthesis?
Temperature, light intensity, carbon dioxide concentration
How and why does temperature affect the rate of photosynthesis?
The rate of photosynthesis increases as the reaction is controlled by enzymes
What happens to the rate of photosynthesis if the temperature gets too high and why?
It will decrease as the enzymes would begin to denature
How does light intensity affect the rate of photosynthesis?
The more light a plant receives, the higher the rate of photosynthesis
How does carbon dioxide affect the rate of photosynthesis?
The more carbon dioxide that is present, the faster the reaction can occur
What do fertilisers do?
Increase the amount of key nutrients in the soil for crop plants, meaning they can grow larger and more healthy, which increases yields
What are pesticides?
Chemicals that kill of unwanted insects and weed species
What do pesticides do?
Ensure that less damage is done to crop plants by insects, as well as reducing competition from other plant species, which increases yields
What are the different types of pesticides?
Insecticides, herbicides, fungicides
What are advantages if using pesticides?
Easily accessible, cheap, have an immediate effect, kills the entire population of pests
What are disadvantages of using pesticides?
Organisms they are meant to kill might develop resistance to them, can kill other beneficial organisms, need to be repeatedly applied, might not break down in the body and can accumulate at the top of food chains in high concentrations
How is yeast used to make bread?
When yeast carries out anaerobic respiration it produces alcohol (ethanol) and carbon dioxide.
Yeast is then mixed with flour and water
Yeast produces enzymes that can break down the starch in the flour, releasing sugars that can be used by the yeast for anaerobic respiration
The carbon dioxide produced by the yeast during anaerobic respiration is trapped in small air-pockets in the dough, causing it to rise
The dough is then baked in a hot oven to form bread
During baking, any ethanol produced by the yeast (as a waste product of anaerobic respiration) is evaporated in the heat
Yeast is killed by the high temperatures used during baking, so no further respiration occurs in the yeast
Once cooled, the bread is ready to be eaten
What are industrial fermenters?
Containers used to grow microorganisms like bacteria and fungi in large amounts
Why and how are asceptic precautions controlled in a fermenter?
Fermenter is cleaned by steam to kill microorganisms and prevent chemical contamination. This ensures only the desired microorganisms will grow
Why and how are nutrients controlled in a fermenter?
Nutrients are needed for use in respiration to release energy for growth and to ensure the microorganisms are able to reproduce
Why and how is the optimum temperature controlled in a fermenter?
Temperature is monitored using probes and maintained using a water jacket to ensure an optimum environment for enzymes to increase enzyme activity.
Why and how is optimum pH controlled in a fermenter?
PH is monitored using a probe to check it is at optimum value for the particular microorganism being grown. The pH can be adjusted if necessary using acids or alkalis
Why and how is oxygenation controlled in a fermenter?
Oxygen is needed for aerobic respiration to take place
Why and how is agitation controlled in a fermenter?
Stirring paddles ensure that microorganisms, nutrients, oxygen, temperature and pH are evenly distributed throughout the fermenter
How is bacteria used to make yogurt?
Lactobacillus is a specific type of bacterium used to make yoghurt
First, all equipment is sterilised to kill other, unwanted bacteria and to prevent chemical contamination
Milk is then pastuerised (heated) at 85-95 C to kill other unwanted bacteria
The milk is then cooled at 40-45 C and lactobacillus bacteria is added
The mixture is incubated at this temperature for several hours, while the lactobacillus bacteria digest milk proteins and ferment (digest) the sugar in the milk
The lactobacillus converts the lactose into lactic acid. This increased acidity sours and thickens the milk to form yoghurt
The yogurt is then stirred and cooled to 5 C to halt the action of the lactobacillus
Flavourings, colourants and fruit may be added before packaging
What happens if the milk get contaminated during the making of yoghurt?
Production could slow down as other bacteria would be competing with the lactobacillus for the lactose in the milk. It could also spoil the taste of the yoghurt
What does lowering the pH in a fermenter do during the making of yoghurt?
Helps prevent the growth of other microorganisms that may be harmful. This means that the yoghurt can be kept for a longer time (compared to fresh milk)
What is selective breeding?
When individuals with desired characteristics are selected by humans to breed together. Offspring that show the desired characteristics are selected and bred together. The process has to be repeated for many succesive generations
What are the 3 characteristics of selective breeding?
Only occurs when humans intervene, results in development of populations with features that are useful to humans and not necessarily the survival or the individual, takes less time as only individuals with desired characteristics are allowed to reproduce
How come there is no alcohol in bread?
During baking the ethanol evaporates in the heat
For what characteristics are plants selectively bred for?
Disease resistance, increased crop yield, hardiness to weather conditions, better tasting fruits, large or unusual flowers
What are the problems with selective breeding?
Can lead to inbreeding
What is inbreeding?
When only the best plants or animals (which are closely related to each other) are bred together
What does inbreeding result in?
A reduction in the gene pool
What is a gene pool?
The of alleles (different versions of genes) in a population
As inbreeding limits the size of the gene pool, what is there an increased chance of?
Organisms inheriting harmful genetic defects, organisms being vulnerable to new diseases (there is less chance of resistant alleles being present in the reduced gene pool)
Explain the use of restriction enzymes
Restriction enzymes isolate the required gene, leaving it with sticky ends.
A bacterial plasmid is cut by the same restriction enzyme leaving it with corresponding sticky ends
The plasmid and DNA have matching sticky ends (because they have been cut by the same restriction enzyme), DNA ligase will link them to form a single, unbroken molecule of DNA
What are plasmids?
Circles of DNA found inside bacterial cells
What are plasmids and viruses examples of?
Vectors
What is a vector?
a DNA molecule that is used as a vehicle to carry a particular DNA segment into a host cell as part of a cloning or recombinant DNA technique
How are viruses vectors?
They transfer DNA into human cells or bacteria
How are plasmids vectors?
They transfer DNA into bacteria or yeast
How can human insulin be manufactured?
The gene for human insulin production is found within a human chromosome
Restriction enzymes are used to isolate the human insulin gene, leaving it with sticky ends
A bacterial plasmid is cut by the same restriction enzyme leaving it with corresponding sticky ends
The plasmid and isolated human gene are joined together by DNA ligase enzyme
The genetically engineered plasmid cell is inserted into a bacterial cell
When the bacteria reproduce the plasmids are copied as well and can quickly spread as the bacteria multiply. They will then all express the human insulin gene and make the human insulin protein
The genetically engineered bacteria can be placed in a fermenter to reproduce quickly in controlled conditions and make large quantities of the human protein
What do plasmids do?
Separate the main bacterial chromosome from the bacteria, making them easy to move and manipulate to insert genes into them and then back inside the bacterial cells
What does transgenic mean?
The transfer of genetic material from one species to another different species
How can genetically modified plants improve food production?
Can produce a poison that kills insects, can be made resistant to certain herbicides, can produce additional vitamins and have improved nutritional value, can be made drought-resistant
