The punnet square below represents the result of the cross between two tall pea plants.

t t
t tt tt
t tt tt t = tall height
t = short height

part a: identify the genotype course & phenotypic ratios of the offspring.

part b: identify two offspring from the punnet square that could produce short pea plants if they were crossed. explain your answer.

Answer

Part a

50% TT, 50% Tt, 100% tall

Part b

Tt x Tt

Explanation:

Part a

The cross is between a homozygous tall pea plant (TT) and a heterozygous tall pea plant (Tt). This produces 2 genotypes at a ratio of 1:1 TT, and Tt. In other words, 50% TT and 50% Tt. These are the same as the parental genotypes, and it means that 100% of the offspring will be tall. (as T  (tall) is the dominant allele.

Part b

A cross between the two heterozygous plants would give the following punnett square:

  T   t

T TT Tt

t Tt   tt

The genotype ratios are 1 TT: 2 Tt: 1 tt, in other words, 25% TT, 50% Tt, and 25% tt. The resulting phenotypes would therefore be 3 tall (TT + Tt): 1 short (tt), or 75% tall, 25% short. This therefore produces some short plants, at a ratio of 25%.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!