Tutor profile: Amina H.
Subject: SAT II Biology E/M
One pond of underground water in Wieliczka salt mine near Krakow, Poland is completely saturated with NaCl. What can you tell me about the organisms that live here? a) they are halophiles b) the environment is sterile c) they can withstand high pressure d) they are very small e) they can be grown in a laboratory
The answer is: b) the environment is sterile Due to the high salinity of the pond, bacteria are unable to survive. High osmotic pressure causes their membranes to burst. The highest recorded halophiles are recorded to be able to withstand only up to 37% of salt in water.
What can you tell me about the blood of an athlete immediately after exercise? One homeostasis is disrupted.
The pH of blood is more acidic due to the increase of CO2 in the lungs. There is a higher concentration of carboxyl acid in the blood thus making the blood more acidic.
Eukaryotes have been known to show the expression of constitutive genes, genes that are transcribed regardless of the environmental conditions or the availability of food. Is there such a thing as a constitutive gene inside the genome of prokaryotes?
If prokaryotes had constitutive genes, creating certain proteins regardless of the conditions, such small organisms would produce proteins that are not necessary at all times. As a result, they would waste energy and nutrients on the production of enzymes that they don't need. Prokaryotes have developed systems called operons that allow them to control the transcription of necessary proteins and suppress the transcription of those not needed at the moment.
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