96 mitosis is the process of cell replication in g1

Info icon This preview shows pages 11–13. Sign up to view the full content.

View Full Document Right Arrow Icon
96. Mitosis is the process of cell replication. In G1, the first phase, the cell grows. The S phase is the DNA synthesis phase in which the chromosomes are replicated, which is followed by G2, in which the cell continues to grow. The cell then enters the mitotic phase. In the
Image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Name _____________________ AP Biology Sample Exam Any School USA Period 8 September 2005 Answer Key first stage of mitosis, prophase, the chromatin condense into chromosomes. The nuclear membrane breaks down, forming vesicles. In the next phase, metaphase, the chromosomes line up on the equatorial plate. The centromeres then divide, separating the sister chromatids, pulling them towards the poles, during anaphase. In telophase, the microtubules disappear and the chromatin recoils. The nuclear envelope redevelops. The cytoplasm divides during cytokinesis, in which the cell membrane pinches inwards, forming two daughter cells. 97. a.) Most mutations are harmful or neutral to their bearers, but if the environment changes, previously neutral or harmful alleles may become advantageous. In addition, mutations can restore alleles to populations that other evolutionary agents removed. Thus, mutations help create and maintain variation within populations. b.) Genetic drift alters allele frequencies primarily in small populations. Organisms that normally have large populations may pass through occasional periods when only a small number of individuals survive, also called bottlenecks. New populations established by a few founding immigrants also have gene frequencies that differ from those in the parent population. c.) The migration of individuals from one population to another, followed by breeding in the new location, produces gene flow. Immigrants may introduce new alleles into a population or may change the frequencies of alleles already present. Emigrants may remove alleles from a population when they leave. 98. a.) A testcross is a cross between a homozygous recessive parent and a dominant parent. The results help to distinguish the genotype of the dominant parent. b.) If the parent were a homozygote dominant, the testcross’ F1 generation would consist of 100% of the progeny with the dominant phenotype. c.) If the parent were a heterozygote dominant, the testcross’ F1 generation would consist of 50% of the progeny with the dominant phenotype, and 50% of the progeny with the recessive phenotype. 99. a.) Patient A most likely is suffering from diabetes, which occurs due to a deficiency of insulin. This results in high levels of glucose in the blood because there is not enough insulin to convert the glucose to glycogen, for storage. A test for glucose, or sugar, in the blood would reveal high glucose levels in diabetics. b.) Patient B most likely is suffering from osteoporosis, which causes bones to become fragile and break. It is often caused by low levels of calcium in the bones, or higher than normal levels of calcium in the blood. An under-active thyroid gland, which secrets calcitonin, or an overactive parathyroid, which secrets PTH, could be responsible. A
Image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern