unit 6 Flashcards
the role of yeast in the production of bread
Anaerobic respiration in yeast cells is called fermentation
yeast is a single cell fungi that uses anaerobic respiration to make bread rise
-when it respires anaerobically is produces ethanol nd co2 if it has plenty of sugar and oxygen
-this is taken advantage when mixed with flour and water
-co2 produce bubbles that causes bread to rise
-ethanol produced as waste product is evaporated
-The yeast is killed by the high temperatures used during baking
This ensures there is no further respiration by the yeast
glucose—ethanol + carbon dioxide
experiment to investigate the role of anaerobic respiration by yeast in different conditions
1) dissolve sugar in boiled water
2) mix yeast to sugar solution in boiling tube
3) add layer of oil-prevent O2 from entering
4) connect boiling tube to test tube of lime water
5) count number of bubbles seen over set time
role of bacteria (Lactobacillus) in the production of yoghurt
- Capable of producing complex molecules (e.g. certain bacteria added to milk produce enzymes that turn the milk into yoghurt)
-they reproduce rapidly, meaning the amount of chemicals they can produce can also rapidly increase
steps to production of yoghurt
1) all equipment sterilized to kill unwanted microorganisms
2) milk is pasteurized-heated to kill any microorganisms in milk, 15 seconds
3) milk cooled and lactobacillus added
4) mixture incubated in fermenter, fermenter- bacteria breaks down into lactose and lactic acid
5) add flavor and package
role and conditions for industrial fermenters
fermenters= containers used to grow microorganisms like bacteria and fungi in large amounts
CONDITIONS=
-aseptic conditions needed to ensure no other microorganisms grow or contaminate container
-nutrients needed for microorganisms to use in respiration
-optimum temperature and pH needed for enzymes to work at high rates but not denature
-stirring with paddles to endure nutrients, 02, temp and pH is distributes evenly
how are glasshouses used to increase yield of crop
enclosed environment that farmers have control over conditions;
1) artificial heating=photosynthesis enzymes work faster
2) artificial lighting
3)increase in Co2 conc.
4) regulate water
how are polythene tunnels used to increase yield of crop
-large plastic tunnels that cover crops
-protect from extreme effects of weather
-slightly increase temp in tunnel
-prevent entry of pests
3 main factors that affect rate of photosynthesis
-temp
-light intensity
-co2 conc
how are fertilizers used to increase yield of crop
-increase amount of key nutrients in soil to make them grow larger/ more healthy
-soil in farming land is deficient
ORGANIC= manure and straw
CHEMICAL= dry granules and sprayed
contain mostly; nitrogen , phosphorus, potassium
nitrogen= makes amino acids, without= weak growth/ yellow leaves
phosphorous= makes DNA and cell membranes, without=poor root growth, discolored leaves
potassium=allows enzyme reaction to happen
without=poor growth/ brown spots
reason for pest control
pests and other animals damages crops. Weed outcompete for space
insecticides
herbicides
fungicides
advantages and disadvantages of pesticides
ADVANTAGES=
-cheap/accessible
-bad for environment-production
-immediate effect
-kills entire population
DISADVANTAGES=
-organisms develop resistance
-often kills other beneficial organisms like bees
-can accumulate in food chains
what is biological control and its advantages and disadvantages
when another organism is introduced to control pests like ladybirds kill greenflies
ADVANTAGES=
-natural, not pollution
-can target specific population
-long lasting
-no need to repeat apply
DISADVANTAGES=
-may eat another organism
-long time
-cannot kill entire population
what is selective breeding and how does it work
it is used to produce organisms with desired characteristics
1) select individual organisms with desired characteristics
2) breed them together
3) select offspring with desired characteristics
4) repeat over many generations
differences between natural selection and artificial selection
NATURAL SELECTION=
1) characteristics selected due to aiding survival
2) population becomes more suited to environment
3) 3) occurs over long period
ARTIFICIAL SELECTION=
1)characteristics selected by humans for desirability
2) population is more useful to humans-unable to survive in wild
3) takes less time
reasons why selective breeding in plants is used
-decrease resistance
-increase crop yield
-tolerance to weather conditions
-more nutritious and larger
PROBELMS= leads to inbreeding
-reduction in gene pool
-inherit genetic defects-harmful
-venerable to new diseases
