Symbiosis Outcome Affected By Environment
What will be an ideal response?
An example of a symbiotic interaction that can have a range of outcomes is present with hydras and algae.
Hydras are small freshwater Cnidarians that live in ponds and slowly moving rivers.
They feed on small animal rotifers present in the water column.
Some hydra are green because they contain algae from the genus Chlorella inside their bodies.
The algae photosynthesize and they release substantial amounts of photosynthetically fixed carbon to the animal cells in the form of maltose (a sugar).
Green hydra can easily be cultivated in the laboratory, and they can also be "bleached" of their algae by incubation at very high light intensity.
Both hydra containing algal cells (symbiotic hydra) and those deprived of their algae (aposymbiotic hydra) reproduce rapidly by asexual budding.
So large numbers of genetically identical symbiotic and aposymbiotic hydra can be generated for experiments.
--performance of green hydra under different conditions of illumination and feeding
-hydra: starved in light (survival)
-symbiotic aposymbiotic >10 weeks, <2 weeks, the hydra benefit
-interaction: + effect on alga, + effect on hydra
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The density of a population is defined as______
a. the number of individuals in a population at a specified time b. the number of individuals in a population at a specified place c. the number of individuals per unit area or per unit volume of habitat d. the size of the individual organisms per unit area e. the number of the individual organisms per unit size of each individual
Which of the following statements correctly describes reverse genetics?
A) A mutated phenotype in an organism leads to the associated gene. B) A mutated gene is introduced into an organism to determine the phenotype. C) A gene is studied to understand the protein it encodes. D) A transcript is used to make a protein encoded by a gene. E) A gene is identified by bioinformatics.
The gene for Tay-Sachs disease codes for a nonfunctional form of the enzyme hexosaminidase A (or Hex
A). It has been found that a person with only one-third the maximum amount of Hex A can function absolutely normally. Please characterize the heredity of Tay-Sachs disease. A) codominant B) recessive C) dominant D) multiple allelic