Question

8 cell structure and function
directions
for multiple - choice questions, write the letter that best answers the question or completes the statement on the line provided. for other question types, follow the directions provided.

1. which of the following statements is part of the cell theory?

a. cells are composed mostly of empty space.
b. cells are generally large enough for the unaided eye to see.
c. all cells are produced from existing cells.
d. only animals are made up of cells.

1. the cells of all organisms contain dna. in cells of which of the following groups is the cellular dna enclosed in a nucleus?

a. bacteria
b. eukaryotes
c. prokaryotes
d. viruses

1. microscopes can be used to explore cells. which of the following types of microscopes can produce a three - dimensional image of the surface of a cell?

a. simple light microscope
b. compound light microscope
c. scanning electron microscope
d. transmission electron microscope

1. a number of scientists made contributions to cell theory. which scientist used a light microscope to observe cells in a slice of cork?

a. anton van leeuwenhoek
b. matthias schleiden
c. robert hooke
d. theodor schwann

Explanation:

Question 1

The cell theory states that all cells come from pre - existing cells. Option a is wrong as cells are not mostly empty space. Option b is wrong because most cells are too small to be seen with the unaided eye. Option d is wrong as both plants and animals (and other organisms) are made of cells. So the correct statement is that all cells are produced from existing cells.

Eukaryotic cells have a nucleus that encloses the DNA. Bacteria are prokaryotes and their DNA is not in a nucleus. Prokaryotes in general (like bacteria) don't have a nucleus - enclosed DNA. Viruses are not cells and don't have a cellular structure with a nucleus. So the group with cells having DNA enclosed in a nucleus is eukaryotes.

A scanning electron microscope (SEM) is used to produce three - dimensional images of the surface of a cell. A simple light microscope and a compound light microscope give two - dimensional images and are limited in magnification. A transmission electron microscope (TEM) is used to look at the internal structures of cells in a two - dimensional cross - section. So the scanning electron microscope is the one that can produce a 3D image of the cell surface.

Answer:

c. All cells are produced from existing cells.

Question 2