# surface/vol ratio, biology homework help

Please complete the labs as requested in the files.

There are few important points for Lab 11

Experiment 1: the purpose is to determine the length of each phase. In general, interphase last really long. It is at least about 75% of the entire cell cycle.You should see most of the cells in interphase in your slide since this phase lasts long. You may not find anaphase or telophase because they are really short. If no, you didn’t recognize different phases correctly. To get help in recognizing mitotic phases, google, type in mitotic phases in onion, you will see tons of them with labels.

1) for calculations, if you see 26 cells in interphase in a total of 36 cells,

the hours spent in interphase is

26/36 X24h=17.33h

2) surface/vol ratio will decrease as cell grows. the ratio will be increased after cell divisions.

Experiment 2: make sure you stay consistent with chromosome numbers in each stage. some students started with 3 chromosomes, and ended up with 2 chromosomes in each daughter cells. Something went wrong in the process.

Experiment 3:

Somatic mutations can’t be passed on to next generations. Only germline mutations dp. That’s why most cancers are not inheritable except for a few that are due to germline mutations, e.g breast cancer caused by BRAC gene mutation that runs in Angelina Jolie’s family.

There is a fundamental defect in Lab 14. In instruction, there are three parts: Part 1 for practicing Punnet square; part 2 for monohybrid and part 3 for dihybrid. But in the download worksheet, there is no table for dihybrid (table 3 and 4). So it caused a lot of confusion.

In the monohybrid exercise, you determined each parent by drawing beads from beaker 1, Y or y.

in dihybrid, you determined each parents by drawing beads two times from beaker 1 (Y/y) and two times from beaker 2(G/g) since there are two traits. (no one has done that due to the defect in the worksheet, so I ignored this exercise)

Some problems:

1. Incomplete example – in the book LDL receptors

Co-dominance- AB blood type

2. The amount of gametes= 2^ (number of genes)

3. Can you tell a person’s genotype by his/her phenotype? Sometimes. .e.g, if you tell me your blood type is O, then I can tell for sure, you must be ii. But if you say your blood type is A type, I don’t know if you are Ai or AA.

4. What is a carrier? A carrier is a a heterozygous individual that carries a recessive allele but doesn’t show the trait coz this trait is masked by the dominant allele.

5. When dealing with genetic crosses, always construct your Punnet square. DO NOT assume!

So, you don’t have to do part 3 in the lab 14.

Please complete the labs directly in attached files