cells - deans community high school homepage€¦ · 4 deans community high school biology...

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Deans Community High School Biology Department N5

Cells

N5

Homework book

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Homework 1

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Homework2 Cell Ultrastructure and Membrane

1. Name and give the function of the numbered organelles in the cell below:

2. Name 3 structures you might find in a plant cell but not in an animal cell.

3. Identify one similarity and one difference between a plant cell and a

fungal cell.

4. A newly discovered species was being classified.

The organism is unicellular, has no organelles and several plasmids. Should it be classified as an animal, a plant, a bacterium or a fungus?

Why?

5. When examining the cells of a carrot under the microscope, which plant

organelle would you not expect to see? Why?

6. Use your own words to describe the structure of the cell membrane.

In your description make sure you include the terms:

bilayer, protein, phospholipid and fluid mosaic.

A

B

C

D

E

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Homework 3

1. The diagram below shows a cross-section of a plasma membrane.

a. Describe the function of the plasma membrane.

b. A plasma membrane is sometimes described as consisting of a phospholipid bilayer. What does

this mean?

c. Draw labels onto the diagram to show the position of a: phospholipid molecule; protein molecule.

d. Suggest one possible job of a protein embedded in the membrane.

e. Plasma membranes are said to be selectively permeable. Explain what this means, giving

examples.

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Homework 4

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Homework 5

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Homework 6

Protein Task to demonstrate secure learning.

Use all you know to make a poster to show how DNA codes for proteins by

following these instructions:

1. Choose one of these DNA sequences (or make up your own)

2. Arrange the DNA sequence into triplets

3. Use the protein decoder (see below or in class) to identify the amino

acids coded for by your triplets

4. Arrange the amino acids in the correct order to form a protein

Your poster must be colourful, informative and in easy to follow steps to

show you understand how DNA codes for a protein.

TACTCGAATCGATTTATC

TACTTAGGCCATGGGACT

TACAGCCGTGTCCCAATT

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Homework 7

1. The diagram below shows a yeast cell.

a. Name the structure shown in the diagram that contains genetic information.

b. In a unicellular organism like yeast, a type of cell division called mitosis occurs. What is the

importance of mitosis to yeast cells?

c. During mitosis the genetic information inside the cell is copied. This is called DNA replication. Why

does this happen?

d. Describe what could happen if a mistake is made during DNA replication and the DNA is incorretly

copied?

2. Mitosis also occurs in multicellular organisms. The graph below shows the results of an

experiment to measure the increase in shoot length of germinating pea plants over a forty day

period.

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a. Which five day period shows the greatest average increase in shoot length?

b. What is the total increase in shoot length between day 15 and day 30?

c. In this investigation a total of one hundred plants were used. Explain why using so many plants

makes the results more reliable.

d. Suggest another way that the student who did this investigation could have measured the overall

growth of the shoots.

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Homework 8

Mitosis Homework

Use the information found at web address shown below to complete the tasks

about mitosis.

http://www.abpischools.org.uk/page/modules/ce

lldiv_cancer/cancer4.cfm

1. Identify three important function of mitosis.

2. Why are the cells in an organism said to be genetically identical?

3. Explain what is meant by a cancer cell.

4. What is a tumour?

5. Describe how medicines used to treat tumours work.

http://www.abpischools.org.uk/page/modules/celldiv_cancer/cancer4.cfm

http://www.abpischools.org.uk/page/modules/celldiv_cancer/cancer4.cfm

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Homework 9

DNA Code Cracking

1. DNA is a code for making proteins.

a. How does the sequence of bases in a DNA molecule control which protein is made?

b. Explain how a mistake during DNA replication could result in the wrong protein being made.

2. The DNA code is copied then translated before a new protein is made. During the copying process

the base Thymine is relaced with a base called Uracil, represented by the letter U. This means that

the codes for amino acids all contain the letter U instead of letter T. Use the genetic code to identify

the amino acids being coded for in each of the sequences below.

See if you can complete this example first:

a. AAAAGUUACUUGGGACCG

Now crack the next two codes!

b. GCCACCAACAGCGUUCAC

c. CUGGGGACUUCCCAGGUG

d. Identify the amino acid that would be inserted into the sequence above if the first base was

changed from a C to an A. (use the table on the last page to help you)

3. The diagram below shows how long chains of amino acids form to make proteins. This model is

actually insulin, which your body needs to control its blood sugar levels. As you can see it is two

separate chains of amino acids joined together by chemical bonds.

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a. In what part of the cell are amino acids joined together?

b. What is the name of the molecule that carries the copy of the DNA code for making

proteins?

c. What name is given to a long chain of amino acids?

d. What kind of chemical bonds join amino acids together?

The genetic code

Name of amino acid Abrreviation Name of amino acid Abrreviation

Phenyalanine Phe Tyrosine Tyr

Leucine Leu Histidine His

Isoleucine Ile Glutamine Gln

Methionine Met Asparagine Asn

Valine Val Lysine Lys

Serine Ser Aspartine Asp

Proline Pro Glutamic acid Glu

Threonine Thr Cysteine Cys

Alanine Ala Tryptophan Trp

Arginine Arg Glycine Gly

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Homework 10

Enzymes 1

1. As you (should) know by now enzymes are made of protein and speed up chemical reactions.

Explain exactly why it is important for enzymes to be the correct shape.

2. Draw a labelled diagram to demonstrate the ‘lock and key’ hypothesis.

3. Enzymes are described as being substrate specific. Explain what this means.

4. The table below shows five enzymes that you may have heard of, along with their substrates and

products. They are all mixed up! Re-draw the table and match the substrate and products up with

the correct enzyme.

5. Four out the five enzyme controlled reactions shown above are degradation reactions. Only one is

a synthesis reaction.

a. Define the terms degradation and synthesis in relation to enzymes.

b. Identify the synthesis reaction from the table above.

c. Describe an example of a synthesis reaction that happens inside your body every day, naming the

substrate, the enzyme and the products.

Substrate Enzyme Product

Fat Pepsin Maltose

Glucose-1-phosphate Lipase Water and oxygen

Starch Catalase Amino acids

Hydrogen peroxide Phosphorylase Fatty acids and glycerol

Protein Amylase Starch

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Homework 11 Enzymes Homework

1. As you (should) know by now enzymes are made of protein and speed up chemical reactions.

Explain exactly why shape is important for enzymes.

2. Define the term ‘optimum conditions’ in relation to enzyme activity.

3. Name three factors that could affect the activity of an enzyme.

4. The graph below shows the results of an investigation carried out by some students into the action of the enzyme catalase on hydrogen peroxide. The students wanted to know how changing the temperature affected the activity of the enzyme.

a. What is the optimum temperature for the activity of catalase? b. Describe what happens to the

activity of the enzyme as the

temperature of the experiment

is increased from 10oC to 55oC.

c. Predict the height of the foam that

would be produced if this experiment

was carried out at 70 oC. Explain your answer.

5) This question refers to the graph below. Enzymes of the digestive system work best at different

pH conditions. In the mouth, pH tends to be neutral so amylase works best at around pH 7. The

stomach is very acidic, with conditions of around pH 2. The enzyme trypsin, found in the small

intestine, works best at about pH 9.

a. Use the letters on the graph to identify

amylase, pepsin and trypsin.

c. Which enzymes would both still work at

pH 8?

d. Enzyme A does not work at pH 6. Why?

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6. The diagram below shows an investigation into the enzyme amylase. Amylase is an enzyme found

in saliva that breaks down starch in food into a sugar called maltose.

a. Suggest one improvement to the way this experiment has been set

up that would make the results more valid.

b. What is the purpose of test tube B?

c. After one hour the water outside of the visking tubing in both test tubes was tested with for the presence of starch and maltose. What results would you expect? Explain your answer for both Tube A and Tube B. d. Suggest two ways that the rate of the reaction in Tube A could be increased. e. The experiment was repeated using the enzyme catalase in test tube A instead of amylase. After

one hour the water outside the visking tubing water tested for the presence of starch and maltose.

What result would you expect in Tube A? Explain your answer.

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Homework 12

Genetic Engineering

1. The diagram below shows some of the stages of genetic engineering which are used to produce

new medicines such as human insulin.

a. Complete the table to identify the labelled parts of the diagram.

Name of Structure Label

Bacterial cell

Plasmid

Insulin gene

b. Describe the next stage of the process needed to create insulin as a medicine, after the gene has

been successfully inserted into the plasmid and the plasmid reinserted into the bacterium.

c. Name another useful product produced by genetic engineering.

d. State two advantages and two disadvantages of genetic engineering.

2. Part of the process of genetic engineering

is shown in the picture opposite.

a. Describe what is happening at this stage.

b. Name an enzyme needed at this stage.

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Homework 13

Proteins

1. Describe the basic structure of a protein molecule. You may draw it but you need to write a

description as well.

2. Name the chemical elements needed to make proteins.

3. Where are proteins made? See if you can find a diagram of one being synthesised and make a

labelled drawing of it.

4. Why do different proteins have different properties?

5. Find out, using the internet, the library or by asking someone (or all three!) about the proteins

keratin and haemoglobin. You should compare them, e.g. what they do, and where they are found

and any other interesting information (a table might be a good way to do this). You should also

explain why they have different properties.

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Homework 14

When peas germinate they carry out aerobic respiration. An investigation to

find out if heat is produced by germinating peas was carried out using the

apparatus below.

The change in temperature inside the

flask was measured over a period of

72hrs. The results are shown below.

1. Calculate the total rise in

temperature. (1)

2. Calculate the average rise in

temperature per hour. (1)

3. Using your graph paper draw a line

graph of the results from the table. (3)

Time (hrs) Temperature (0C)

0 18

12 26

24 40

36 48

48 50

60 52

72 54

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4. What conclusion can be drawn from these results? (1)

5. Why would it be necessary to set up a control for this experiment and what

would make a suitable control? (In other words, how can you tell that the peas

are responsible for the heat that is produced?) (1)

6. State one factor which must be kept the same in order for the control

experiment to be a valid comparison. (1)

7. Respiration can be described as a two stage process.

a. What molecule is glucose broken down into during the first stage?(1)

b. How many ATP are produced in the first stage? (1)

c. How many ATP are produced in the second stage? (1)

d. Name the waste products of respiration. (1)

8. Name four uses of ATP by cells. (2)

9. How could the rate of respiration in animals be measured? (1)

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