Science 9 Review Worksheet 4.1
1. What is the function of a cell membrane?
The cell membrane controls what enters and leaves the cell.
2. Describe the structure of a cell wall.
The cell wall is a tough and rigid structure surrounding the plant cell membrane. It is composed of
cellulose.
3. What is an organelle?
An organelle is a part of a cell that has some specific job or function.
4. What is the function of mitochondria?
Mitochondria perform the process of respiration. They take in glucose and oxygen and burn them to
release the energy in glucose for the cell to perform all its functions.
5. What is the function of a ribosome?
A ribosome manufactures proteins.
6. Where do proteins go after they are made on the endoplasmic reticulum?
Proteins from the E.R. are sent to the Golgi Body where they are modified and packaged to be sent out of
the cell.
7. What is the function of the nucleus?
The nucleus controls the growth and development of the cell.
8. What are the parts of the DNA molecule?
DNA is made up of nitrogen bases, phosphates and sugars.
9. Describe how bases pair up in the DNA molecule.
In DNA, A pairs up with T and G pairs up with C.
10. What is chromatin?
Chromatin is the substance that makes up chromosomes. It is composed of DNA and protein.
11. How many chromosomes does a human body cell contain?
The human body contains 46 chromosomes, 23 pairs.
12. What are genes?
Genes are small parts of a strand of chromatin or of a chromosome that make a certain trait of an
organism. Each gene actually has a code that makes a particular protein.
13. Where are genes located?
Genes are located on chromosomes (chromatin). They are from hundreds to thousands of bases long.
14. Your retina cells (at the back of the eye converting light energy into electrical impulses) and
muscle cells (shrink in length when stimulated) contain identical DNA. How are these cells able
to function differently?
Different DNA becomes active and is used to make different proteins in retina cells and muscle cells.
Science 9 Review Worksheet 4.1
15. What must occur before a new protein is made in the cell?
A segment of DNA in chromatin makes an RNA copy of itself. This RNA copy goes from the nucleus to
to the cytoplasm where it links to ribosomes. The ribosomes use the RNA copy to build a unique protein
according to the RNA code.
16. What is RNA?
RNA is a molecule both similar to and different from DNA. It copies the DNA base code and moves to
the cytoplasm where gets used by ribosomes to make a protein according to the RNA code.
17. How is the message carried from the nucleus to the ribosomes?
RNA carries the DNA code for what protein to make to the ribosomes in the cytoplasm where the
ribosomes follow the RNA copy’s instructions.
18. What happens to a protein once it is made?
A protein made by ribosomes on the E.R. is exported out of the cell while a protein made by free-floating
ribosomes is used within the cell. Any protein can be used for the cell’s structure or for its functions (to
do special jobs).
19. What is the function of the Golgi body?
The Golgi body modifies proteins sent to it from the E.R. and puts membrane packages around those
modified proteins which then get sent out of the cell.
20. Identify the job or function of the structure below:
The Golgi body modifies proteins and puts membrane packages around them.
21. Identify the job or function of the structure below:
The chloroplast performs the process of photosynthesis. It captures sunlight energy and stores it in a
sugar it makes, glucose, made from carbon dioxide and water.
Science 9 Review Worksheet 4.1
22. Identify the job or function of the structure below:
The nucleus controls the growth and development of a cell.
23. Identify the job or function of the structure below:
The mitochondrion performs the process of respiration. It burns glucose by using oxygen and releases the
energy from glucose so the cell has energy to do all its life processes.
24. Draw a diagram that shows the relationship between a chromosome and a gene.
A gene is a small part of a chromosome. There are thousands of genes on a chromosome.
25. What do the genes in a cell do? What is their function?
Genes cause the development of certain traits or features in an organism. Specifically, a gene causes the
production of a certain protein. What proteins get made determine what a cell develops into.
26. How is the information contained in the DNA transported out of the nucleus?
The DNA information (code) is copied into RNA and then RNA moves out the nuclear pores into the
cytoplasm to ribosomes.
27. Where are the ribosomes located that manufacture proteins for transport out of the cell?
Ribosomes on E.R. make proteins that are transported out of the cell.
Science 9 Review Worksheet 4.1
28. In the diagram below, identify which part is the phosphate, the sugar, and the base.
Parts a and d above are the nitrogen bases. Part b above is a sugar. Part c above is a phosphate.
29. Draw a nucleus and label the nuclear membrane, nuclear pores and chromatin.
30. Explain how the nucleus controls the functions of life.
The code of the DNA in the chromatin (chromosomes) determines the RNA copy which tells the
ribosomes what kinds of proteins to make. DNA code  RNA copy code  Specific Protein
31. What makes the structure and function of a skin cell different from a nerve cell?
The kinds of protein that get made in a skin cell are different than in a nerve cell. This happens because
different parts of the DNA get activated in these two kinds of cell.
32. The protein hemoglobin, which carries oxygen in red blood cells, is not made in a skin cell.
Explain why.
In a skin cell, different parts of the DNA in the nucleus get activated which makes different RNA and thus
different proteins.
33. Predict what might happen to a cell if a required protein was not made in that cell.
A cell might not develop properly. It might die.
Science 9 Review Worksheet 4.1
34. One side of a DNA molecule contains the following sequence of bases:
ACCTGCTAT
Write the sequence of bases on the other side of the molecule.
TGGACGATA
35. In which part of the DNA molecule would a change be more damaging to the cell: in the sugarphosphate sides of the molecule or in the A,G,C,T bases? Explain.
A cell would be damaged more by a change in the bases (A,G,C,T) because the base order is a code that
causes a specific protein to be made. Different proteins cause cells to develop differently.
36. Explain why DNA cannot leave the nucleus.
The cell needs to constantly refer to DNA instructions as it grows and develops. The DNA is like a
library of information about what the cell needs to do. It is important that this DNA information does not
leave the nucleus and get lost.