Does diffusion occur in only one direction, or can one substance diffuse in one direction, and a second substance diffuse in the opposite direction? What is your evidence? Give specific examples. What determines the direction of diffusion?

Angiosperm reproduction relies on animals, wind, gravity or secretion to convey pollen grains from the male to the female organ. However, researchers have studied one species of orchid that is entirely self-reliant for its reproduction. The orchid rotates its anther in order to insert pollen into its own stigma cavity then rotates the anther back, against gravity, to its original position. List 3 different physical features of the orchid that would be consistent with its complete dependence on self-fertilization. Explain the 3 choices.

1. True or False? Plants take up nitrogen from the atmosphere in the same way that they take up atmospheric carbon.

2. Large animal aggregations such as bird colonies, herds of large herbivores, and shoals of fish provide "safety in numbers" from predators. As a result, individuals in larger groups have higher survival & greater rates of reproduction than individuals in smaller groups. This represents an example of which of the following?

A. Positive density dependence

B. Negative density dependence

C. Density independent population regulation

D. None of the above

3. Legumes contain nitrogen-fixing bacteria in their roots that increase soil nitrogen for use by other species. This is an example of:

A. inhibition

B. tolerance

C. facilitation

D. suppression

You are measuring the titer (i.e. plaque-forming units (PFUs) of the Rabid Wolverine Virus within the bloodstream of Ohio State fans, and you measure the following numbers from blood drawn from one Buckeye (Ohio State) fan. In each case below, you have plated 1 mL of the blood or diluted blood on a plate containing a confluent monolayer of tissue culture cells that are susceptible to the virus. You allowed the plates to incubate overnight, and upon arriving at the lab early the next morning you count the plaques on each plate. Your results are the following:

- the plate with the undiluted blood sample resulted in too many plaques to count

- the plate with the 10-fold dilution of the blood sample resulted in too many plaques to count

- the plate with the 100-fold dilution of the blood sample resulted in approximately 3000 plaques

- the plate with the 1000-fold dilution of the blood sample resulted in 298 plaques counted

- the plate with the 10,000-fold dilution of the blood sample resulted in 32 plaques counted

Which of the following best describes the titer of the Rabid Wolverine Virus within the bloodstream of the single Buckeye (Ohio State) fan you tested?
3 x 10⁹ plaques / mL
3 x 10⁷ plaques / mL
3 x 10¹ plaques / mL
3 x 10⁵ plaques / mL
3 x 10³ plaques / mL

The coding region alone for the important BRCA1 tumor supressor gene in humans contains 5,592 bp (base pairs) of DNA in the coding region. Mutations in the BRCA1 gene associate with breast and ovarian cancer in humans and "carriers" of BRCA1 mutations have a ~50-65% chance of developing breast cancer by age 70.

with the above info alone calculate (i) the predicted number of amino acids for the encoded BRCA1 protein, and (ii) predict the molecular weight of the BRCA1 protein in kDa, using the average amino acid molecular weight.

Discuss ocean acidification with respect to coral reefs. Thank you !

Gene duplication, as part of plant nuclear genome evolution, is considered an important contributor to total gene number and to overall genome size. In recent plant nuclear genome evolution, and post gene duplication, is sub-functionalisation or specialisation believed to be the mostly likely contributor to increased gene number in plant species with larger sized genomes? Explain your answer.

1. In terms of response time and antibody production, how is a primary immune response different from a secondary immune response?
2. What is a difference between a pathogen and an allergen?
3. How is an autoimmune disorder different from an allergy?

1. What are the 3 differences between innate immune response and adaptive immune response.
2. What the two lymphocytes that are important for adaptive immunity? Where do they originate, and develop?
3. Why is it important to have a diversity of lymphocytes?

1. Describe the 3 levels of defense mechanisms.
2. Describe the importance of mast cells, complementary proteins and phagocytes in inflammatory response.
3. Why is the lymphatic system important for the immune system?

D. Using a molecular biology based approach; foreign pieces of DNA can be readily integrated into the nuclear genomes of a number of plant species via the use of the Agrobacterium tumefaciens (Agrobacterium) Tumour-inducing (Ti) plasmid and its encoded Transfer-DNA (T-DNA). For the Agrobacterium Ti plasmid and T-DNA to be used successfully for the introduction of foreign DNA to the plant nuclear genome, some gene sequences need to be retained while others must be removed. Please state; (1) which gene sequences are retained and which are removed; (2) the position (Ti plasmid-based or T-DNA-based) of the retained and removed sequences, and; (3) explain why some gene sequences must be retained while others require removal.

Transposons and retrotransposons are two prominent classes of repetitive DNA in the nuclear genome of plants. Both of these repetitive DNA species are capable of moving throughout the plant nuclear genome via transposition. Describe the mechanism of transposition for each of these mobile DNA elements and further, which is considered one of the main contributors to increased nuclear genome size and which is more likely to influence gene expression post transposition. Explain your answer.

A. The vast majority of the DNA sequence of a plant nuclear genome is composed of repetitive DNA with only a small fraction of the genome space representing protein coding gene sequences. Discuss the structure of chromatin in repeat-rich and gene-rich regions of the plant nuclear genome, including the methylation status of the DNA in these two distinct genome regions. Also, describe the conformational change in chromatin structure required to promote gene expression and explain why this conformational change is required.

Summarize the steps of cellular respiration (glycolysis, TCA cycle and electron-transport chain) identifying the starting material and end product for each stage, where in the cell it takes place, energy requirements and energy yields for each stage, and coenzymes involved in each stage.