At the end of your biology class, your professor asks you to develop a project to determine the genotype of a plant with red flowers. Red petal color (R) is dominant to pink flower color (r). To accomplish this task, you cross the plant with the unknown genotype with heterozygous red-flowered plants. Which of the following are valid predictions of the ratio of flower colors in the offspring? partially filled Punnett square is provided.

The question lacks options and the incomplete punnet square; the incomplete punnet square has been added as an attachment while these are the options:

A) All red flowers

B) All pink flowers

C) 1 red : 3 pink flowers

D) 3 red : 1 pink flowers

The answer is D

Explanation:

According to the question, the genotype of a plant that produces red flower phenotype is about to be determined. For this flower colour gene, two alleles are involved in which the red color (R) allele is dominant over the pink color (r) allele I.e. the R allele will mask the expression of r allele in a heterozygous state.

The red-flowered plant with unknown genotype was crossed with a heterozygous red-flowered plant (Rr). Since a red flowered plant can either be Rr (heterozygous) or RR (homozygous), we use the Rr plant in the punnet square. The unknown genotype, assuming it has a Rr genotype, will produce RR, Rr, Rr and rr offsprings when crossed with another heterozygote (Rr).

These offsprings show a 3 red : 1 pink phenotypic ratio, making option D a valid prediction.

         R        r

R      RR     Rr

r       Rr     rr

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!