Fig 1. Developmental Scheme for use in Questions 1a and 1b. The entire organism is shown and individual cells are indicated. A very small number of the genes expressed in some cells are highlighted (for example, the gene ‘apc' is expressed in three cells in Stage 1). Stage 1 is in early development, and Stage 3 is later in development though not yet an adult.

Developmental scheme

The developmental scheme in Fig 1 shows three stages in development.

1a) How do you know that [aspect of development] is happening? Limit answers to ~3 sentences, maximum, and avoid extra information that is not relevant.

1b) Describe signaling that could reasonably be happening in Fig 1. Be as specific as possible, and feel free to describe molecules and genes that are not shown in the diagram. Answer in 2-3 sentences, max.

1c) Draw a diagram of an additional developmental stage for this organism. This stage should clearly demonstrate [withheld**].

2) You are trying to bio-engineer a virus to carry particular genes between human cells. The virus must not only be able to move between cells and copy-and-carry particular genes, but it also should have as small of a genome as possible so that it can make many copies of itself. Which of the following aspects of viruses will be important for this bioengineered vector?
Mark the two best answers.

Explain why the aspects you picked are the most crucial in 1-3 sentences, max.

3)

Mark all correct answers.

Killer T-cells     Helper T-cells      B-cells

Mast Cells      Neutrophils and/or macrophages      Dendritic cells

Explain your answer(s) in 1-2 sentences.

4) What parts of the human immune system defend against [pathogen or threat withheld].

Mark all aspects of the immune system that are needed to respond specifically to this threat. You can ignore aspects of the immune system that are generally helpful but which would not be effective in this case.

Histamines

The VDJ region of the DNA

Skin and mucus-covered physical barriers

Concisely explain how your chosen aspects can work together to respond to this threat in 2 sentences, max.

5a) Fig 2 shows several stages of development within a mammalian ovary. Describe, in 1-3 sentences, how [developmental process withheld] happens. You can do this in general terms; you do not need lots of specific anatomic terminology in order to get full points.

5b) Once the released oocyte is successfully fertilized, it will continue a lineage of cells into the next generation. Imagine the lineage from this zygote to a single cell in the adult brain. [Question about this lineage of cells withheld]. Explain your answer in 1-3 sentences.

5c) In a different developing mammal, you find both evidence of infection by the Zika virus and signs of developmental difficulties in that mammal's brain. Which of the following pathways is the most likely method by which the Zika virus could have caused a difference in development?

Choose the single best answer:

Example answer: Zika virions bind to a receptor normally found on the surface of a few cells known to produce lipid soluble transcription factors. These TFs normally upregulate neuron growth.

Explain your answer to 5c in 1-2 sentences, maximum.

6) You are in a lab studying the entire fertilization process in the sea urchin species. You're especially interested in a particular mutant urchin, in which the [specific mutation withheld].

Draw a diagram that clearly shows the differences between normal sea urchin fertilization and sea urchin fertilization in this mutant. You do not need to show every detail, but rather only show/label the differences.

7) The ocean during a sea urchin spawning event is particularly interesting, so you are wading at the beach when you step on an urchin...big ouch. A few of the urchin gametes floating in the water enter your bloodstream.

7a) Which of the following are likely to happen? Mark all correct answers.

7b) Explain which of these answers is the most concerning to your health? Explain in 1-2 sentences why you picked that single most concerning choice.