Hydra and Obelia are cnidarians (species of aquatic organisms) that belongs to the Class Hydrozoa.
Several ways in which Obelia differs from Hydra are;
- Hydra is a predative species that lives on substrates such as wood, while Obelia is a colonial species that lives as polyps on branched frameworks.
- Hydra is found in freshwater habitats, while Obelia is found in marine habitats.
- Hydra undergoes the medusa form in its life cycle, while Obelia undergoes the two forms (polyp and medusa) in its life cycle.
- Hydra has great regenerative powers while Obelia does not have great regenerative powers.
Symbiosis is defined as a win-win relationship between two different species.
B- Win-win is the correct answer.
Dad: TtBb
Mom: ttbb
You have to use distribution for dihybrid crosses. Meaning, the first allele of each trait has a equal chance of being paired with the other allele of the other trait. So for example with Dad, I will number the traits:
T(1)t(2)B(3)b(4)
To set up the possibilities from Dad, it would be 13, 14, 23, 24: TB, Tb, tB, tb. Same idea goes for Mom, except since all alleles are the same, you only need to make one column for Mom, since if you did all 4, the other 3 would just be repeats of the 1.
Cross:
tb
TB TtBb
Tb Ttbb
tB ttBb
tb ttbb
The phenotypic ratio is 1 Tall Brown: 1 Tall Blue: 1 Short Brown: 1 Short Blue
magma drive plate tectonics
Some isotopes, however, decay slowly, and several of these are used as geologic clocks. Dating rocks by these radioactive timekeepers is simple in theory, but the laboratory procedures are complex. <span>All methods rely on the fact that certain elements (particularly uranium and potassium) contain a number of different isotopes whose half-life is exactly known and therefore the relative concentrations of these isotopes within a rock or mineral can measure the age.</span>
