Question

a. match each term below with its definition. write the correct letter on the line.

1. chemical bond
2. cell
3. molecule
4. element

a. the smallest, most basic unit of life
b. matter that is made of only one kind of atom
c. a force that holds atoms together
d. two or more atoms that are joined by chemical bonds
b. label the parts of the microscope using the terms from the box.
eyepiece objectives stage mirror coarse adjustment knob fine adjustment knob
critical thinking
if you were looking for signs of life on another planet, what elements would you look for? explain your answer on a separate sheet of paper.

Explanation:

1. A chemical bond is a force that holds atoms together, so 1 - c. A cell is the smallest, most basic unit of life, so 2 - a. A molecule consists of two or more atoms joined by chemical bonds, so 3 - d. An element is matter made of only one kind of atom, so 4 - b.
2. The top - most part where you look through is the eyepiece (5). The large knob for rough focusing is the coarse adjustment knob (6). The parts that can be rotated to change magnification are the objectives (7). The flat part where the specimen is placed is the stage (8). The part used to reflect light is the mirror (10). The small knob for fine focusing is the fine adjustment knob (9).
3. For signs of life on another planet, carbon is crucial as it is the basis of organic molecules in life on Earth. Oxygen is needed for respiration in many life - forms. Hydrogen is part of water and many organic compounds. Nitrogen is important for proteins and nucleic acids. Phosphorus is a key component of DNA, RNA, and ATP.

Answer:

1. 1. c
2. a
3. d
4. b
5. 5. eyepiece
6. coarse adjustment knob
7. objectives
8. stage
9. fine adjustment knob
10. mirror
11. Carbon, oxygen, hydrogen, nitrogen, phosphorus.