Life history theory examines trade-offs between the components of fitness. Birth weight is one life history trait that can be influenced by these trade-offs. Describe in detail one trade-off that has implications for variation in human birth weight.

What lines of reasoning support the hypothesis that the first self-replicating systems were based on RNA molecules?

What kinds of evidence support the three-domain concept of life?

What evidence supports the idea that the mitochondrion and chloroplast were once free-living members of the domain Bacteria?

Building on Dr. Allisons work on Sickle Cell anemia Dr. Pauling tested hemoglobin from diseased individuals, normal individuals and heterozygotes using ____________ technique.

State 2 incidence of mass poisoning of humans that involved arsenic. What are some of the uses of mercury and what is the aspects bioaccumulation of mercury?

Describe the contrasting roles of Rac and RhoA in regulating cell migration.

Why do small seeds commonly need “high quality” light exposure to germinate? What does “high quality” light mean from a plants perspective??

Vertebrates have a gene called Pax6, and this gene codes for a protein that functions as a transcription factor. Where-ever Pax6 protein is produced in young embryos, an eye develops. a. Where would the Pax6 gene be normally expressed in this embryo? b. If one could cause the Pax6 gene to be expressed on the stomach of an embryo, what do you suppose would happen? c. Pax 6 protein is a transcription factor. What does that mean in terms of protein function? d. Eye development is complicated, and it includes lots of cell  cell signaling (inductions). How is it that a transcription factor can result in cell to cell signaling?

There are a number of credible sources of information that someone could use to learn more about the science of a topic like cancer. The Internet is often a good place to start, but you have to be careful about whether a source of information is reliable. The C.R.A.P. Test () is a useful tool to check the Currency, Reliability, Authority, and Purpose of Internet sources. Here are a few sites you can begin with, but there are certainly many others. Use the websites and videos to learn more about cancer and find information that will help you answer the questions below.

Websites • American Cancer Society: • Cancer Quest: • Centers for Disease Control and Prevention: • Medline Plus: • National Cancer Institute: • Susan G. Komen Foundation: Videos • Amoeba Sisters. “The Cell Cycle and Cancer” (7:41) • Cancer Treatment Centers of America. “What is Cancer?” (6:35) • CancerQuest. “Animated Introduction to Cancer Biology (Full Documentary)” (12:07) • Healthchanneltv. “Breast Cancer—Symptoms and Treatments” (2:34)

Questions

1. What is cancer and how does it relate to the cell cycle?

2. What are proto-oncogenes and tumor suppressor genes, and how do they contribute to cancer?

3. What are some things that might make a person have a higher risk of developing cancer?

4. What are some of the major steps that occur in the progression from a single cancer cell to a tumor and then to many tumors spreading throughout the body?

5. As tumors grow and spread, the cells undergo a number of changes. How might the cells in a late-stage tumor be different from the original cell that became cancerous?

6. Why are different types of cancers named based on where in the body they originate (breast cancer, skin cancer, bone cancer, etc.)? Why does it matter from which organ or tissue type cancer developed?

Please answer the questions and use reliable sources to back up your answer that are shown in the text above. And answer ALL questions 1-6, thank you.

Outline and describe the essential detection methods to investigate these microbial causative agents in a food sample:  

1. E. coli
2. Staphylococcus aureus
3. Salmonellae

QUESTION 5

As the novel coronavirus (COVID-19) pandemic continues to spread and large parts of the world are under lockdown, livestock producers are working hard to maintain production in the face of many uncertainties.

(A) Discuss five (05) ways in which COVID-19 is impacting the livestock industry in the world. (5 Marks)

(B) Discuss five (05) ways in which African Swine Fever outbreaks are similar to Covid-19 infections (5 Marks)

(C) Define Biosecurity? List eight (08) biosecurity measures you would enforce on an intensive pig production farm

1. If this insertion is within the coding region of a viral protein, will this insertion result in a frameshift for the rest of the protein? How do you know?

2. The insertion mutation is in a gene that codes for a protein on the surface of the virus, probably a glycoprotein. Assume that this protein is involved in attachment to a host cell. How might a change in a protein involved in attachment change the potential hosts for the virus?

3. How long does it typically take a person's adaptive immune system to make antibodies in a primary response to an antigen? Is it likely that a person would have memory B cells that recognize a new surface protein on the virus? Why or why not?

4. Why is a population unlikely to have herd immunity to a virus that has a new protein on its surface?

What are the differences between protein expression in prokaryotic organisms vs. eukaryotic organisms

QUESTION 3

(A) In dairy production, what do you understand by the term ‘lactation cycle’? (1 Mark)

(B) Mention the four (04) phases of the lactation cycle and highlight the specific time periods when these phases occur in dairy cows (4 Marks)

(C) Explain how milk production varies in the different phases of the lactation cycle (4 Marks)

(D) Relate the milk production to the feed intake and body weight of the dairy cow during the four phases of the lactation cycle (8 Marks)

(E) Briefly explain the term ‘negative energy balance’ and when does this normally happen in dairy cows (2 Marks)

(F) What is the recommended time of servicing the dairy cow during her lactation cycle?