Topic 1 Cell Structure.

Question 1

What is a cell, what is it surrounded by and what does it contain?

Answer 1

A cell is a basic unit of all living organisms; it is surrounded by a cell surface membrane and contains genetic material (DNA) and cytoplasm-containing organelles.

Question 2

What is an organelle? Give two examples.

Answer 2

An organelle is a functionally and structurally distinct part of a cell e.g. a ribosome and mitochondrion.

Question 3

What are eukaryotes? Give examples of eukaryotes.

Answer 3

An organism whose cells contain a nucleus and other membrane-bound organelles is a eukaryote.
Eukaryotes include animals, plants, fungi, and some other organisms.

Question 4

What are prokaryotes? Give examples of prokaryotes.

Answer 4

An organism whose cells do not contain a nucleus or any other membrane-bound organelles is a prokaryote.
Prokaryotes include bacteria.

Question 5

What is a nucleus (plural: nuclei)?

Answer 5

A large organelle found in eukaryotic cells.
The nucleus contains the cell’s DNA and therefore controls the activities of the cell. It is surrounded by two membranes which together form the nuclear envelope.

Question 6

What are the features that animal and plant cells have in common?

Answer 6

• Cell surface membrane.
• Nucleus.
• Cytoplasm.
• Mitochondria (singular: mitochondrion).
• Golgi apparatus.

Question 7

Cell surface membrane sometimes referred to as the plasma membrane:

• What cells are surrounded by a very thin cell surface membrane?
• What is the function of the cell surface membrane?

Answer 7

• All cells, including those of both eukaryotes and prokaryotes, are surrounded by a very thin cell surface membrane.
• It is partially permeable and controls the exchange of materials between the cell and its environment.

Question 8

Nucleus:

• What cells contain a nucleus?
• Is the nucleus visible through a microscope and why?
• What is the reason for this visibility through a microscope?

Answer 8

• All eukaryotic cells contain a nucleus.
• The nucleus is very easy to see when looking down the microscope because it is a relatively large structure, that stains intensely.
• The nucleus is visible through a microscope because it contains deeply staining material called chromatin and a deeply staining area called the nucleolus.

Question 9

What is chromatin and what does it contain?

Answer 9

Chromatin is a mass of coiled threads. The threads collect together to form chromosomes during nuclear division.

Chromatin contains DNA (deoxyribonucleic acid), the molecules which contain the instructions (genes) that control the activities of the cell.

Question 10

What is the nucleolus (plural: nucleoli), how many can be found inside the nucleus and what is its main function?

Answer 10

The nucleolus is a small structure usually visible as a densely stained body found inside the nucleus.

One or more of which can be found inside the nucleus.

Its function is to manufacture ribosomes using the information in its own DNA.

Question 11

What is protoplasm?

Answer 11

All the living material inside the cell is called protoplasm.
Therefore cytoplasm + nucleus = protoplasm.