Module 5 Cell Division

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Lesson Summary

In this lesson the following focusing questions were examined

• What are the advantages or disadvantages of different reproductive strategies?
• Why do organisms vary their reproductive strategies?

 

Organisms can reproduce quickly and effectively with mitosis and asexual reproduction. The resulting offspring may takeover a habitat and the whole species will benefit by a sheer growth in numbers. However, the entire population will be genetically identical. They may thus all be susceptible to a virus or disease and experience rapid death.

 

To balance the need for high numbers of offspring and to reproduce quickly, many organisms include a part of their life cycle that requires meiosis and sexual reproduction. This increases genetic variability and allows for offspring that are different from their parents. Some of these organisms may not be susceptible to a disease or a change in the environment that hurts the general population. These organisms will live to reproduce again.

 

Some organisms can change their strategies depending on conditions. This allows for the best of both reproductive worlds. When conditions are good, mitotic or asexual reproduction can quickly help colonize an area. However, when the conditions become unfavorable, meiosis or sexual reproduction will allow for genetic variation that will help the species survive.

 

Diploma Connection

Answer the following questions from a previous Biology 30 Diploma Exam.

 

Use the following information to answer the next question.

- from Campbell, 1993

 

1.   Which structures in the life cycle of the Ulva are haploid (monoploid)?

A.  Zoospores and the zygote

B.  The sporophyte and the zygote

C.  Zoospores and the gametophytes

D.  The sporophyte and the gametophytes

 

Use the following information to answer the next two questions.

 

2.   In humans, what process must have occurred to obtain the cells at U?

A.  Mitosis

B.  Meiosis

C.  Fertilization

D.  Differentiation

 

3.   In humans, what process must occur before cell V forms cells W and X?

A.  Mitosis

B.  Meiosis

C.  Recombination

D.  Nondisjunction

 

Use the following information to answer the next question.

 

Numerical Response

4.   Identify the stages in the conifer life cycle, as numbered above, that correspond with the letters that represent these stages on the diagram.

 

Stages:                       _____             _____             _____             _____

Diagram:                    A                     B                     C                     D

 

Use the following information to answer the next question.

 

5.   The row below that identifies the chromosome number at the first stage and the chromosome number at the second stage is

Row	First stage	Second stage
A.	diploid	haploid
B.	diploid	diploid
C.	haploid	diploid
D.	haploid	haploid