Biology Junction Team - BIOLOGY JUNCTION

Decimals, Fractions and Percentages

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Decimals, Fractions and Percentages

Decimals, Fractions and Percentages are just different ways of showing the same value:

A Half can be written…

As a fraction:	1/2
As a decimal:	0.5
As a percentage:	50%

A Quarter can be written…

As a fraction:	1/4
As a decimal:	0.25
As a percentage:	25%

Here, have a play with it yourself:

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Example Values

Here is a table of commonly occuring values shown in Percent, Decimal and Fraction form:

Percent	Decimal	Fraction
1%	0.01	1/100
5%	0.05	1/20
10%	0.1	1/10
12½%	0.125	1/8
20%	0.2	1/5
25%	0.25	1/4
331/3%	0.333…	1/3
50%	0.5	1/2
75%	0.75	3/4
80%	0.8	4/5
90%	0.9	9/10
99%	0.99	99/100
100%	1
125%	1.25	5/4
150%	1.5	3/2
200%	2

Conversions

From Percent to Decimal

To convert from percent to decimal: divide by 100, and remove the “%” sign.

The easiest way to divide by 100 is to move the decimal point 2 places to the left. So:

From Percent	To Decimal
		move the decimal point 2 places to the left, and remove the “%” sign.

From Decimal to Percent

To convert from decimal to percent: multiply by 100, and add a “%” sign.

The easiest way to multiply by 100 is to move the decimal point 2 places to the right. So:

From Decimal	To Percent
		move the decimal point 2 places to the right, and add the “%” sign.

From Fraction to Decimal

The easiest way to convert a fraction to a decimal is to divide the top number by the bottom number (divide the numerator by the denominator in mathematical language)

Example: Convert 2/5 to a decimal

Divide 2 by 5: 2 ÷ 5 = 0.4

Answer: 2/5 = 0.4

From Decimal to Fraction

To convert a decimal to a fraction needs a little more work.

Example: To convert 0.75 to a fraction

Steps	Example
First, write down the decimal “over” the number 1	0.75 / 1

Then multiply top and bottom by 10 for every number after the decimal point (10 for 1 number, 100 for 2 numbers, etc)	0.75 × 100 / 1 × 100
(This makes it a correctly formed fraction)	= 75 / 100
Then Simplify the fraction	3 / 4

From Fraction to Percentage

The easiest way to convert a fraction to a percentage is to divide the top number by the bottom number. then multiply the result by 100, and add the “%” sign.

Example: Convert 3/8 to a percentage

First divide 3 by 8: 3 ÷ 8 = 0.375,
Then multiply by 100: 0.375 x 100 = 37.5
Add the “%” sign: 37.5%

Answer: 3/8 = 37.5%

From Percentage to Fraction

To convert a percentage to a fraction, first convert to a decimal (divide by 100), then use the steps for converting decimal to fractions (like above).

Example: To convert 80% to a fraction

Steps	Example
Convert 80% to a decimal (=80/100):	0.8
Write down the decimal “over” the number 1	0.8 / 1

Then multiply top and bottom by 10 for every number after the decimal point (10 for 1 number, 100 for 2 numbers, etc)	0.8 × 10 / 1 × 10
(This makes it a correctly formed fraction)	= 8 / 10
Then Simplify the fraction	4 / 5

Line Graph Quiz

%CODE1% Line Graphs Quiz

Click on the radio buttons in front of the correct answers to the questions.

Line Graph of Temperatures

Bar Graph Animated title

BAR GRAPHS

When you have finished this page, try the Bar Graphs Quiz.

Bar graphs are an excellent way to show results that are one time, that aren’t continuous – especially samplings such as surveys, inventories, etc. Below is a typical survey asking students about their favorite after school activity. Notice that in this graph each column is labeled – it is also possible to label the category to the left of the bar.

In this case, the numbers for each category are across the bottom of the chart.

A bar chart is marked off with a series of lines called grid lines. These lines typically mark off a numerical point in the series of numbers on the axis or line. In this case, each grid line going up and down marks a multiple of 20 as the graph is divided such.More gridlines can make it easier to be exact with the amounts being shown on the bar graph, but too many can make it confusing.

Notice that for data that does not fall evenly on a multiple of 20, the bar is in between two grid lines.

Bar graphs are useful to get an overall idea of trends in responses – which categories get many versus few responses.

Favorite Student After School Activity

Activity	Number
Visit W/Friends	175
Talk on Phone	168
Play Sports	120
Earn Money	120
Use Computers	65

BAR GRAPH QUIZ

Click on the radio buttons in front of the correct answers to the questions about the graph.

Bar Graph

Circle Pie Graph Title CIRCLE/PIE GRAPHS

When you have finished this page, try the Circle/Pie Graphs Quiz.

Circle or pie graphs are particularly good illustrations when considering how many parts of a whole are inception. In the table below both the number of hours in a whole day devoted to certain activities is listed as well as the percent of time for each of these activities. The pie chart is then divided very much as a baker’s pie would be into slices that represent the proportional amounts of time spent on each activity.

To the right of the pie chart is a legend that tells which color stands for which category. In addition, the percents are also near the pie slice that stands for that particular amount of time spent.

Percent of Hours of a Day Spent on Activities

ACTIVITY	HOURS	PERCENT OF DAY
Sleep	6	25
School	6	25
Job	4	17
Entertainment	4	17
Meals	2	8
Homework	2	8

Pie Graph of Day's Activities

Circle/Pie Graph Quiz

Click on the radio buttons in front of the correct answers to the questions.

Chart of Day's Activities

Quiz – Biochemistry

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	Biochemistry Quiz
	1. All of the following are carbohydrates EXCEPT: starch glycogen chitin cholesterol2. The structure contains which functional group aldehyde ketone amino carboxyl 3. Fatty acids that are unsaturated have: an amino group a double bond an excess of protons a carboxyl group 4. The structure below is a: monosaccharide disaccharide lipid polymer 5. Which of the following can have a quaternary structure? fatty acid protein polysaccharide DNA 6. An organic compound is one that: contains carbon is slightly acidic forms long chains is soluble in water 7. Which of the following elements is the LEAST abundant in living organisms? oxygen nitrogen phosphorous sodium 8. Which of the following is used in PET scans? uranium ions isotopes steroids 9. Carbon can form ___ separate bonds with other elements? 1 2 3 4 10. The cohesion of water is caused by: ionic bonds hydrophobic compounds hydrogen bonds covalent bonds Score = Correct answers:

Flat and Roundworms Study Guide

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Name:

Flat and Roundworms Quiz

Multiple Choice
Identify the choice that best completes the statement or answers the question.

Planarians can reproduce asexually by

a.	fission.	c.	producing polyps.
b.	forming larvae.	d.	exchanging both sperm and eggs.

Which of the following is not found in flatworms?

a.	an anterior end	c.	bilateral symmetry
b.	a circulatory system	d.	a nervous system

Flatworms have no need for circulatory and respiratory systems because

a.	the digestive system performs these functions.
b.	their cells are close to the animal’s exterior surface.
c.	the spherical body shape allows diffusion of materials into tissues.
d.	the coelom is bathed in blood and oxygen.

Schistosomiasis is a disease caused by a

a.	roundworm.	c.	cestode.
b.	trematode.	d.	planarian.

turbellarians : free-living ::

a.	planaria : parasitic	c.	cestodes : free-living
b.	tapeworms : free-living	d.	flukes : parasitic

Which of the following statements about tapeworms is false?

a.	They can infect a person who eats undercooked food.
b.	They belong to the genus Schistosoma.
c.	They can grow to be large in human intestines.
d.	They do not have a digestive system.

To which phylum do roundworms belong?

a.	Annelida	c.	Platyhelminthes
b.	Nematoda	d.	Arthropoda

Roundworms have a fluid-filled cavity called a

a.	coelom.	c.	digestive system.
b.	pseudocoelom.	d.	None of the above

Roundworms have a digestive tract with ____ opening(s).

a.	three	c.	one
b.	two	d.	no

10.

All of the following groups of invertebrates are coelomates except

a.	annelids.	c.	mollusks.
b.	echinoderms.	d.	nematodes.

11.

A roundworm’s digestive tract can be considered an advancement over a gastrovascular cavity because

a.	food moves through it in only one direction.
b.	different parts of the tract can carry out different functions.
c.	undigested wastes do not have to leave through the same opening where food is taken in.
d.	All of the above

12.

The nematode Ascaris lumbricoides infects humans, spending most of its adult life inside the intestines of its host. To be infected, a person must

a.	consume the nematode’s eggs.
b.	walk barefoot on infested soil.
c.	sit on an infested toilet seat.
d.	All of the above

13.

A type of roundworm that lives a parasitic life is

a.	Ascaris.	c.	Trichinella.
b.	Enterobius.	d.	All of the above

14.

A rotifer uses ____ to collect excess water in order to remove the water from the body.

a.	diffusion
b.	kidneys
c.	flame cells and excretory tubules
d.	a mastax

15.

Which of the following statements is not true?

a.	Most tapeworms are hermaphrodites.
b.	Planarians reproduce both sexually and asexually.
c.	Some rotifers reproduce by parthenogenesis.
d.	Because they are all parasitic, roundworms reproduce asexually.

16.

Tapeworms absorb food from the host through their

a.	scolex.	c.	suckers.
b.	tegument.	d.	None of the above

17.

Humans can avoid trichinosis by

a.	avoiding undercooked meat.
b.	avoiding public restrooms.
c.	wearing shoes outdoors.
d.	washing their hands frequently.

18.

Which of the following has a cloaca?

a.	a fluke	c.	a rotifer
b.	a nematode	d.	a tapeworm

19.

Parasitic flatworms

a.	probably evolved from free-living organisms.
b.	gave rise to free-living flatworms.
c.	have a gut with two openings.
d.	are found mostly in the class Turbellaria.

20.

Which of the following is not true about the planarian nervous system?

a.	It includes a ladderlike arrangement of nerves.
b.	It provides the ability to sense light intensity.
c.	It includes one ventral nerve cord.
d.	It provides the ability to learn.

Completion
Complete each statement.

21.

A schistosome is a member of the phylum ____________________.

22.

The ability of some animals, such as flatworms, to regrow lost parts of their bodies is called ____________________.

23.

Flatworms take up oxygen and release carbon dioxide by the process of ____________________, which occurs across the body surface of the animals.

24.

The ____________________ is a protective cellular covering of the bodies of endoparasitic flukes that prevents them from being digested by their hosts.

25.

____________________ are rectangular body sections of tapeworms.

26.

Roundworms are members of the phylum ____________________.

27.

Roundworms take in food through the mouth and eliminate wastes through an opening at the other end of the digestive tract called the ____________________.

28.

Organisms that feed by using cilia to sweep food into their mouths are called ____________________.

29.

____________________ are the simplest animals with bilateral symmetry.

30.

Concentration of sense organs at the anterior end can be observed in flatworms and is called ____________________.

31.

A planarian takes in food through the ____________________.

32.

The ____________________ is a noncellular layer that protects a roundworm.

33.

Being infected with ____________________ worms can cause a condition known as elephantiasis.

Essay

34.

A planarian cannot eat when food is already in its gut. Why? Write your answer in the space below.

Quiz Viruses

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Name:

Viruses

True/False

Indicate whether the sentence or statement is true or false.

Although viruses do not consist of cells, biologists consider them to be living because they are capable of reproduction.

Some viruses have a membranous envelope surrounding the protein coat that helps them gain entry into host cells.

Viruses consist of RNA or DNA surrounded by a coat of protein.

Prions are the smallest known particles that are able to replicate.

A virus can only reproduce by controlling a cell.

Once a virus enters either a lytic or a lysogenic cycle, it cannot change to the opposite type of cycle.

Prophages and proviruses can both enter lytic cycles and destroy host cells.

People can contract the influenza virus more than once because the virus tends to mutate rapidly, avoiding the actions of the immune system.

Smallpox is caused by bacteria.

10.

Chickenpox and shingles are caused by the same virus.

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

11.

The study of viruses is a part of biology because

a.	they belong to the kingdom Eubacteria.
b.	they are about to become extinct.
c.	they are living organisms.
d.	they are active inside living cells.

12.

The capsid of a virus is the

a.	protective outer coat.	c.	nucleus.
b.	cell membrane.	d.	cell wall and membrane complex.

13.

A membranous envelope surrounding some viruses may be composed of

a.	lipids.	c.	glycoproteins.
b.	proteins.	d.	All of the above

14.

viruses : nucleic acids::

a.	water : ice	c.	simplicity : complexity
b.	brick : wood	d.	a jigsaw puzzle : individual pieces

15.

A typical virus consists of

a.	a protein coat and a cytoplasm core.
b.	a carbohydrate coat and a nucleic acid core.
c.	a protein coat and a nucleic acid core.
d.	a polysaccharide coat and a nucleic acid core.

16.

Refer to the illustration above. Which labeled structure could possibly be made of RNA?

a.	Structure “B”	c.	Structure “D”
b.	Structure “C”	d.	Structure “E”

17.

In which type of cell cycle(s) does viral DNA become integrated into the host cell’s DNA?

a.	lytic	c.	neither lytic nor lysogenic
b.	lysogenic	d.	lytic and lysogenic

18.

A prophage differs from a provirus in that

a.	a prophage contains DNA, while a provirus contains RNA.
b.	a prophage is formed during a lysogenic cycle, while a provirus is formed during a lytic cycle.
c.	a prophage contains DNA found in the infecting virus particle, while a provirus contains DNA produced from viral RNA.
d.	a prophage becomes integrated into a host cell’s DNA, while a provirus cannot become integrated into a host cell’s DNA.

19.

Which of the following is not a virus linked to cancer?

a.	Ebola	c.	hepatitis B
b.	human papillomavirus	d.	Epstein-Barr

20.

Which of the following human activities is most closely associated with emerging viruses?

a.	absence of a vaccination program	c.	clearcutting of forests
b.	crowded living conditions	d.	eating uncooked meat