1. Below are pictures of two molecules. X shows a glucose molecule and Y shows a benzene molecule. The black balls represent Carbon atoms, the white balls represent Hydrogen atoms, and the red balls represent Oxygen atoms.
Which choice best explains which molecule will dissolve in water and why?2. Most lipids don't dissolve in water, while most carbohydrates do.
Why?3. The picture below shows two polysaccharides. Branched polysaccharides (such as glycogen) can be more easily separated into individual chains than can linear polysaccharides (such as cellulose).
This is explained by the increased number of4. Many lipids have a polar “head” and non-polar “tail.” The blue color in the diagrams below represents water.
Which structure do lipids form in water?6. A short piece of protein and a short piece of DNA are shown above.
What do these molecules have in common?8. The diagrams below show pairings of nucleotide bases.
Which nucleotide pair has the strongest attraction and why?9. An mRNA molecule is created using a specific gene.
This mRNA11. There are four nucleotide bases in DNA (A, T, G, and C). Each DNA triplet in a gene (such as AGT or CCG) codes for an amino acid. There are 64 different combinations of DNA triplets possible, but there are only 20 different amino acids used in organisms.
Which statement is the best explanation of why there are more triplets than amino acids?13. A silent mutation in a gene has no effect on the amino acid sequence of the protein produced by the gene.
Why?17. Press Run on the model above to see how this short protein chain folds into its final shape.
Which amino acid substitution is most likely to change the way this protein folds?18. Which amino acids affect the primary function of a protein once it has finished folding?
The amino acids...19. When a protein and another molecule have matching surfaces, they can form a stronger attraction.
This is because the matching surfaces allow20. The model above shows a protein. The binding site is indicated by the yellow circle.
What can you predict about the ligand (small partner molecule) that will be associated with the binding site?
The ligand will21. Some diseases occur because of misfolded proteins.
This is because misfolded proteins22. Many drugs work by attaching to proteins in our bodies via weak attractive forces.
What are the most important factors in designing one of these drugs?23. A drop of blue dye is added to a container of clear water. After several hours, all of the liquid in the container is light blue.
At this time, the molecules of dye25. Diffusion is key to how your kidneys work. Kidneys filter waste products out of the blood to form urine.
Why is it an advantage to have a large surface area between the blood that is being filtered and the ducts that collect waste?
Larger surface areas allow for26. Imagine a cell that has a membrane through which potassium ions freely enter and leave. Suppose this cell contains a high concentration of potassium and is put in distilled water that has no potassium.
Which is the BEST description of what will happen?
Potassium ions will28. If you place a carrot in salt water, it will become soft and "wilted."
How does the process of osmosis explain why this happens?29. One of the many uses of ATP is to push ions across membranes, causing an increase in electrical energy.
Why is ATP needed to make this happen?30. The image below shows some of the reactions involved in breaking down glucose.
Which of the reactions shows ATP being produced?31. A sequence of chemical reactions, including some that occur during glycolysis, is shown below.
How many steps show NADH being used up?34. The chemical reaction for the production of ATP is shown below.
ADP + Pi ---> ATP + H2O
What is true of this reaction?36. Plants have a number of pigments, such as chlorophyll and carotenoids, each of which can absorb light.
What is the advantage of having different pigments?37. Why does a green leaf photosynthesize better under red light than under green light?
Pigments in the green leaf