Which of the following crosses would always result in offspring that only display the dominant phenotype? tt x tt tt x tt tt x tt tt x tt both a and c

both A and C

Explanation:

To know whats happens with all the offspring and the probabilities you need to draw Punnett squares.

We will call T the dominant trait and t the recessive.

TT x tt = Tt Tt Tt Tt = 100% Tt

100% of the offspring will show the dominant allele.

Tt x Tt = TT Tt tT tt =25% TT 50% Tt 25% tt

Here, you have 25% chances that the offspring shows the recessive allele.

TT x TT = TT TT TT TT= 100% TT

100% of the offspring will show the dominant allele.

Tt x tt = Tt tt tt tt = 25% Tt 75% tt

Here, you have 75% chances that the offspring shows the recessive allele.

which

what is a measurement of the earth’s history divided into time periods?

> fossil record <

sedimentary rock

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radioactive elements

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.