Unit 1 check
Unit 1 check: Chemistry of Life
10 questions from 7 lessons in Unit 1. Answer each one, and if you miss, follow the link back to where it is taught, then try again. Your score counts first tries.
Question 1 · from 1.1 · Fill the statement
Complete the description of a model of two neighboring water molecules.
Inside each molecule, the solid lines are bonds. The oxygen atom is labeled partially . The dashed line from a hydrogen of one molecule to the oxygen of the other is a bond.
Question 2 · from 1.2 · Fill the statement
Complete the description of the elements in biological molecules.
The three most common elements in carbohydrates, proteins, lipids and nucleic acids are carbon, hydrogen and . Phosphorus is used to build phospholipids and . A sugar such as glucose is built from carbon, hydrogen and oxygen .
Question 3 · from 1.3 · Sort it
Each card describes part of a reaction. Tap a card, then the reaction it belongs to.
Dehydration synthesis
Hydrolysis
Setup for question 4
A new question about the same idea. A cell builds a single branched polysaccharide from 30 simple sugars by dehydration synthesis. The finished molecule has a main chain and 4 side chains.
Question 4 · from 1.4 · Calculate
How many water molecules were released in building it?
Setup for question 5
A new situation. A student grows the same kind of bacteria at two temperatures and measures what share of the fatty acids in their membranes are unsaturated. These numbers are a teaching example.
- Grown at 10 °C: 72% of membrane fatty acids are unsaturated
- Grown at 37 °C: 45% of membrane fatty acids are unsaturated
Question 5 · from 1.5 · Calculate
The share of unsaturated fatty acids in the bacteria grown at 10 °C is how many times the share in those grown at 37 °C? Give your answer to one decimal place.
Setup for question 6
A new sample. A lab finds the bases in a nucleic acid from a virus. These numbers are a teaching example.
- Adenine (A): 30%
- Uracil (U): 18%
- Guanine (G): 25%
- Cytosine (C): 27%
- Thymine (T): none
Question 6 · from 1.6 · Decide and justify
Is this virus's nucleic acid double-stranded DNA?
Which reason supports your decision?
Setup for question 7
A researcher makes four versions of an enzyme that differ only at position 42, a spot in the enzyme's folded core, and measures each version's activity under the same conditions. These numbers are a teaching example.
| Version | R group at position 42 | Activity (% of normal) |
|---|---|---|
| Normal | Hydrophobic | 100 |
| Version 1 | A different hydrophobic R group | 97 |
| Version 2 | Hydrophilic (polar) | 38 |
| Version 3 | Ionic | 6 |
Question 7 · from 1.7 · Calculate
Using the table: version 2's activity is how many times version 3's? Give your answer to one decimal place.
Question 8 · from 1.1 · Match
Match each property of water to the observation it best explains.
Question 9 · from 1.2 · Match
Match each element to what a cell uses it to build.
Setup for question 10
Two new situations. First, a student puts an unbranched chain of 50 monomers in a tube with an enzyme that hydrolyzes some of its bonds. When the reaction stops, the tube holds 10 shorter chains, each 5 monomers long, and no single monomers.
Second, another student hydrolyzes a polymer in water whose oxygen atoms have been tagged so they can be traced. Before the reaction, the polymer holds no tagged oxygen.
Question 10 · from 1.3 · Calculate
How many water molecules did the hydrolysis use?
0 of 10 answered.