Thursday, October 14, 2010

Plant Review Questions for Exam 2

Review Questions about Plants:
1. Compare and contrast the movement of water and food in plants. Include in your answer what kinds of tissues and processes are involved in both.

2. Xylem is functional when dead at maturity while phloem is functional only when alive. Why?

3. In phloem, what is the role of the companion cell?

4. What is the difference between xylem in flowering plants and the xylem found in gymnosperms?

5. What is cohesion of water, and how is this different from adhesion?

6. What part of the root absorbs water?

7. What is the function of the anther in the flower?

8. Which of the following is where one would find ovules?
A. in an anther
B. in the ovary
C. in the stigma
D. in the style

9. Ovules are
A. eggs
B. spores that will become pollen
C. spores that will become eggs
D. immature seeds
E. pollen grains

10. In double fertilization the first sperm fertilizes the egg and the second
A. dies
B. is only used if the first sperm cell dies
C. fertilizes another egg
D. fertilizes a haploid endosperm mother cell to make diploid endosperm
E. fertilizes a diploid ( n+n) endosperm mother cell to make triploid endosperm

11. What is the function of fruit?

12. Microspores become
A. the embryo sac
B. the mature male gametophyte
C. pollen grains
D. all of the above
E. only B and C above

Review questions Bio 120 exam 2

Mitosis and Meiosis Review

1. If a cell has 8 chromosomes and does mitosis, how many cells will be made, and how many chromosomes will each cell have?

2. If a cell has 8 chromosomes and does meiosis to make sperm cells, how many cells will be made, and how many chromosomes will each cell have?

3. Mitosis creates cells which are ________, while meiosis makes cells which are _____.

4. What are homologous chromosomes?

5. What are sister chromatids?

6. What is crossing over, and during which process, (mitosis or meiosis) does it occur?

7. Why is crossing over important?

8. During __________ of mitosis sister chromatids separate.

9. During _________ of meiosis homologous pairs of chromosomes separate, but during ____________ of meiosis sister chromatids separate.

10. In meiosis, typically four sperm cells are made, but meiosis only makes one large egg cell. Why?

DNA Review Questions

1. Describe the structure of the DNA molecule

2. If the sequence of bases on one stand of the molecule is AAC TGC CCG, what is the sequence on the complemetary strand?

3. During DNA replication, what enzyme breaks the hydrogen bonds between the base pairs, and what enzyme matches up nucleotides to the existing ones on the parent strand of DNA?

4. Why is this type of replication called Semi Conservative?

5. How is RNA different from DNA?

6. The production of messenger RNA from DNA is called ________, and this happens in the __________ of the cell.

7. The parts of the mRNA molecules which are edited out before RNA reaches the cytoplasm are called __________

8. mRNA gets a cap and a tail prior to being read by the ribosome. What is the function of the cap and tail?

9. If the DNA strand being copied had this sequence: ACT GGC ATA CTA what would the sequence of the mRNA be?

10. The function of transfer RNA is ?

11. What is the name of the enzyme that produces RNA from DNA?

12. If the sequence of DNA is the same in your body cells, why are all cells not the same?

13. The DNA in you, an earthworm, and a fungus is the same. So why are you a human and not an earthworm?

14. What is an anti-codon and where is it found?

15. The protein synthesis process that occurs at the ribosome is called _____________

16. What is a stop codon?

Genetic Engineering

1. What are restriction enzymes?
2. What kind of cells have restriction enzymes, and what is the purpose of these enzymes in the cell?
3. What is a plasmid?
4. How are plasmids used in genetic engineering?
5. Why does human DNA work in a bacterial cell?
6. What is gene therapy?

Friday, October 8, 2010

Global warming and the tropics

We have all heard in the news about the stresses global warming and the associated climate changes are causing organisms in the north. The polar bear has become some what of a poster child for the impacts of global warming in the north. However,researchers are now reporting on the impacts even small changes in the tropics can have on animals there.

The tropics teem with insects which are ectotherms. These animals vary their metabolic rate with their environment. As the environment warms, their metabolism rises, and they need to eat more. The most current estimate I know of places the number of insect species in the tropics at about 3.7 million. This is a huge reduction from the previously held estimate of 30 million. The real number would be somewhere in between the two I suspect.

In any case, there are millions of insects that are being affected by warming. Why does this matter? Insects are key to life in the tropics. They play all kinds of important roles. They are a rich source of food for other animals, they are pollinators of the flowering plants that dominate the tropics, and some keep the population numbers of other species in check.

As warming causes their body temperatures to rise, their metabolic rates rise and they have to eat more, or reduce their activity to conserve the food they have.

To see a Science Digest article about this topic click here.