1. THE EFFECT OF TEMPERATURE ON THE HATCHING SUCCESS OF BRINE SHRIMPS

2. Brine shrimp ecosystem
At beginning of unit 5 you would have set up a brine shrimp ecosystem
To introduce the concept of ecosystems
To investigate how biotic and abiotic factors affect an ecosystem
Linking the learning to AS!
What are biotic and abiotic factors?

3. Brine shrimp ecosystem:
Primary producers: microscopic algae
Primary consumers: brine shrimps
Decomposers: microorgansims
Light energy= self sustaining
Algae photosynthesise: grow, multiply by asexual reproduction
Provides food and oxygen for brine shrimps
Algae are recycled by microrganisms: carbon dioxide
When population density of algae is high= abundant food (green water!)
Population increases exponentially=mounting competition for food, (clearer water)
Population fluctuation=equilibrium reached

4. Abiotic vs biotic factors
A species lives in a particular habitat because it is adapted, able to survive and reproduce there.
Within these habitats species compete.
The conditions in which species compete for survival are defined by the ecological factors in their habitat
Abiotic or biotic factors: synoptic
So linking in with climate change you need to know how to investigate the effect of temperature on Organisms

5. This links in with Investigating the effects of climate change:
Learning outcomes
Describe how to investigate the effects of temperature on the development of organisms.
The effect of temperature on the hatching success of brine shrimps (Core) (Practical)
This links in with Investigating the effects of climate change:
Investigating the effects of temperature on organisms, could be animals (brine shrimps) or plants: you could be questioned on both/either! Seedling growth rate/Brine shrimp hatch rate
Also The effect of temperature on the initial rate of an enzyme catalysed reaction: links in with this topic too
ALL use enzyme explanations in the conclusion!

6. Effect of temperature on the rate of typical enzyme catalysed reactions

7. Why are brine shrimps suitable organisms for Biological research?
What are the ethical implications?
1 Rights and duties
Every individual, born or unborn, has the right to life. Parents have a duty to meet this right.
A mother has the right to continue or not continue with a pregnancy, particularly if the pregnancy presents risks to the mother’s physical or mental health.
Parents have the right to make a free and properly informed choice about whether or not to abort a fetus found to have a significant disorder.
2 Maximising the amount of good in the world
It is unethical to bring a child with a severe genetic disease into the world if this will result in substantial suffering of the individual, greatly reduce the happiness of parents and family, or drain the financial resources of society.
Allowing a child with a genetic disease to be born may replace the possibility of a healthy child being born. Selecting healthy children will strengthen, rather than weaken, the gene pool, reducing the number of faulty genes in the population.
3 Making decisions for yourself
It is up to the parents to decide if they are willing and able to have a child that will require a special commitment of care.
4 Leading a virtuous life
Virtuous parents would perhaps love and care for their child irrespective of their physical or mental capacities. Virtuous relatives and families would help them.

8. Brine shrimps:
Brine shrimps hatch in 24 hours at temperatures between ⁰C with an optimum of 28 ⁰C
Short life cycle: one year
Ability to remain dormant for long periods
Small, easily available
Ethical
Brine Shrimp are most likely not complex enough to suffer physical and mental stress. Nevertheless, there is still debate over whether or not animals should possess rights as humans do. Due to a lack of consent from the shrimp, we can instead try to minimise the amount of suffering by considering animal welfare. The purpose of the investigation can be justified if the shrimps don’t suffer as much. We can minimise the suffering by:
Returning the shrimps to their natural habitat after use
Storing the shrimps in conditions that replicate their natural environment
Working at a good pace to minimise time shrimps are under any possible stress
Turning off the bright light when not in use
Not using an excessive temperature

9. Risk assessment Ethical considerations of organisms Equipment?
Chemicals

10. Task 1:What do you need to consider?
HYPOTHESIS: As temperature increases, the rate of hatching success of brine shrimps also increases until optimum temperature is achieved
Independent Variable: Temperature of each sample (water baths at 10°C, 15°C, 20°C, 25°C and 30°C will be used)
Dependent variable= number of hatched shrimp
Control variables and how you can control them to keep them constant:
Salinity :Amount of sea salt used – 2g used (weighed using weighing scale)
Volume of water used – 100 cm³ of de-chlorinated water will be used each time
Number of brine shrimp eggs – roughly 40 should be used in each beaker
Light intensity – all beakers placed in same area with equal amounts of light exposure
Time – each sample of eggs will be left for exactly 24 hours pH
Presence of chlorine from tap water: salinity (Drinking water has a Florida DEP limit of sodium chloride salinity of less that 0.5 ppt (410 ppm)
Oxygen concentration: use a probe to measure dissolved oxygen concentration
Use of data logging on variables
4. Control: hatch in salt water that is 2-5% salt (optimum 2.8%), pH 8.5, oxygen must be present. Light is not essential for hatching OR Control: The sample left at 25°C can be the control as this replicates standard room temperature

11. Evaluation issues:
Difference in light intensity (random error) – can all be placed in dark room with one dim light source covering all samples equally
Death of eggs due to natural causes (random error) – carry out repeats to make results more reliable
Some eggs may not be viable anymore and won’t hatch
Fluctuating temperatures
Not accurate salt measurements
May not have counted exactly 40 eggs
May miss seeing some of the baby shrimp
LIMITATIONS
The bright light source that was used to count number of hatched larvae may have heating effect which may affect the hatching rate of brine shrimps and alter the results.
The beaker contents need constant aeration in order to provide sufficient amount of oxygen for the cysts to hatch and to keep the cysts in suspension.
Counting the number of egg cysts is a tedious work. The eggs might overlap each other and make it hard to count leading to inaccurate number of eggs being put into the test tube

12. Results/data
The majority of the shrimp should hatch at the optimum temperature between 25°C and 30°C.
A Spearman’s Rank statistical test for a correlation can be carried out to determine the statistical relationship.
You should observe that hatching success rate increases with increasing temperature up to the optimum, after which the success rate decreases
We will look at Q10 and initial rate of reaction in the enzyme/temperature experiment

13. Conclusion
The hatching success with respect to temperature can be explained in terms of enzymes:
A low temperature provides less kinetic energy to the enzymes so fewer enzyme-substrate complexes are formed in the same amount of time. Therefore, fewer product molecules are produced. This is the reason why increasing temperature initially increases the rate of development and so hatching success.
The peak of the graph indicates the optimum temperature. This is when enzymes have the greatest amount of kinetic energy they can have whilst maintaining their protein structure. At this point, the enzymes are working most efficiently and effectively.
Beyond this optimum temperature, the protein structure starts to change. Large amounts of kinetic energy overcome the hydrogen bonds in the tertiary and secondary structures of the proteins. This causes the enzyme to change shape and so the shape of the active site is also altered. For this reason, fewer substrates can bind to form enzyme-substrate complexes. This is why increasing the temperature beyond a certain point slows down the rate of development.

14. (b) This experiment will need to run for a few days
(b) This experiment will need to run for a few days. Explain how you would both control and monitor the incubation temperature over this time. THINK
(b) The experiment would best be run in incubators set at the required temperatures.
This can be problematic at temperatures below room. A refrigerator might be suitable, they usually run at about 5°C.
If such equipment is not advisable a thermostatically controlled water bath can be used.
Failing both of these, flasks can be located in places, which are likely to experience different temperature regimes.
In all cases it might be wise to monitor temperature.
This is least necessary in an incubator where the set temperature should be maintained.
In all cases it would best be achieved using temperature probes attached to a datalogger.
If, again, such equipment is not available, regular readings can be taken to give some idea of the variation experienced.

15. Complete exam questions: