Q: If a DNA sample contains 30% adenine, what percentage of guanine does it contain?

$$100\% - (30\% \text{ adenine} + 30\% \text{ thymine}) = 40\%$$; guanine is half of this, so $$20\%$$

Question 1

Which of the following best describes the hierarchy of biological organization from smallest to largest?

Accepted Answer

Organelle, cell, tissue, organ, organism, population, community, ecosystem, biosphere

Question 2

A scientist is testing the effect of a new fertilizer on plant growth. She sets up three groups: one with no fertilizer, one with the standard fertilizer, and one with the new fertilizer. Which group serves as the negative control?

Accepted Answer

The group with no fertilizer

Question 3

Given an atom with atomic number $$Z = 17$$ and atomic mass $$A = 35$$, how many neutrons does it have?

Accepted Answer

$$A - Z = 35 - 17 = 18$$ neutrons

Question 4

Which of the following statements about covalent and ionic bonds is correct?

Accepted Answer

Covalent bonds involve the sharing of electrons, while ionic bonds involve the transfer of electrons.

Question 5

A solution has a pH of 5.0. How many times greater is its $$[H^+]$$ concentration compared to a solution with pH 7.0?

Accepted Answer

$$10^{(7.0 - 5.0)} = 100$ times greater

Question 6

Which property of water allows a water strider to walk on the surface of a pond without sinking?

Accepted Answer

Surface tension due to hydrogen bonding

Question 7

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Hydrogen bonds stabilize and keep water molecules farther apart in ice than in liquid water

Question 8

Which functional group is correctly matched with its structure?

Accepted Answer

Carboxyl group: $$-COOH$$

Question 9

Which of the following statements about isomers is correct?

Accepted Answer

Structural isomers differ in the covalent arrangements of their atoms.

Question 10

A protein loses its three-dimensional structure when exposed to high heat. What is this process called?

Accepted Answer

Denaturation

Question 11

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose sugar, while RNA contains ribose sugar.

Question 12

If a DNA sample contains 30% adenine, what percentage of guanine does it contain?

Accepted Answer

$$100\% - (30\% 	ext{ adenine} + 30\% 	ext{ thymine}) = 40\%$$; guanine is half of this, so $$20\%$$

Question 13

Which of the following is a difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have membrane-bound organelles; prokaryotic cells do not.

Question 14

Which organelle is responsible for the synthesis of proteins that are exported from the cell?

Accepted Answer

Rough endoplasmic reticulum

Question 15

Which cytoskeletal element is primarily responsible for cell movement and muscle contraction?

Accepted Answer

Microfilaments (actin filaments)

Question 16

Which of the following best describes the flow of energy through an ecosystem?

Accepted Answer

Energy enters as sunlight and exits as heat.

Question 17

Which of the following is a trace element essential for human health?

Accepted Answer

Iron (Fe)

Question 18

Which of the following best describes a buffer in biological systems?

Accepted Answer

A substance that minimizes changes in pH by accepting or donating H$$^+$$ ions

Question 19

Which of the following is true about the synthesis of polysaccharides, fats, and proteins?

Accepted Answer

They are synthesized by dehydration reactions and degraded by hydrolysis.

Question 20

Which of the following is found in plant cells but not in animal cells?

Accepted Answer

Cell wall

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