International Baccalaureate

Standard Level Biology

Using this Revision Guide

Welcome to the International Baccalaureate Standard Level Biology Revision Guide, 2016 edition.

The format is clear, colourful and simple to follow. Key points, facts and principles are listed for easy learning, and diagrams are designed to make them easy to learn and reproduce in an exam. Remember that a clear diagram provides an instant essay plan therefore helping you to gain the extra mark for clarity and organisation.

Although the guide covers every aspect of the Standard Level course the layout does not follow the sequence of the syllabus. Instead it has been reorganised to follow a more developmental sequence as Chapters, starting with Mathematical Requirements, Molecular Biology, Cell Biology, Cell Metabolism, and Human Physiology. These are followed by Ecology, Genetics and finally Evolution and Biodiversity.

'Pale blue boxes' contain information that helps with understanding by providing additional information. However you do not need to learn this.

I

J Other 'coloured boxes', such as these green and yellow ones,

-...;;;;;;;;;;;;;;;;;;;;;;;;;;;;.....J, contain information that you do need to know.

� This means you need to be � able to 'draw' the diagram or

diagrams.

This means you need to be able to 'identify' the diagram when it is given in an exam question.

'Annotate' means adding some further information to the labels.

This is your revision book, so every few pages are sets of 'Grey Box Questions'. These contain simple questions and you should be able to complete these. The answers are at the end of the chapter.

24. What type of cell division do prokaryotic cells

use?

In addition to these there are a few larger 'Revision' boxes. Krebs Cycle

At the end of each chapter there are a number of Self-test Quizzes, containing 'multiplechoice questions'. A suggested way to approach revision would be to work your way through a chapter and test yourself with the Grey Box Questions. Then at a later date check how much you have really learnt by trying the Self-test Quizzes. Remember that when you answer multiple choice questions NEVER choose the first one that sounds right. Examiners sometimes put in a trick answer as A or B. Always read ALL four answers and try to think of the reason why the other three are wrong. The answers are in Appendix 1 on pages 210-12.

Chapter Two Molecular Biology Part 1 Carbon, water, carbohydrates, lipids

Molecular Biology looks at four major groups

of biological molecules - carbohydrates, lipids,

proteins and nucleic acids.

All organic molecules are based on the carbon atom.

Section

Molecules

Hydrophilic and hydrophobic

Amphipathic

Carbon

Water

Comparing the thermal properties of water and methane

Water as a heat transporter

Water as a habitat

Water as a coolant

Water as a transporter in blood

Water as a transporter in plants

Carbohydrates

Monosaccharides and disaccharides

Polysaccharides

Cellulose

Starch

Lipids

Triglycerides

Fatty acid structure

Phospholipids

Steroids

Carbohydrates and lipids as energy stores

Scientific evidence for health risks of trans fats and saturated fatty acids

Evaluation of evidence for health claims about lipids

Methods used to obtain evidence

Condensation and hydrolysis

Condensation and hydrolysis in carbohydrates

Condensation and hydrolysis in lipids

Condensation and hydrolysis in amino acids

Body mass index (BMI)

Are you the right weight?

Molecular visualisation software

Glossary

Answers to Grey Box Questions

Self-test Quiz

Answers to Self-test Quiz

IBSL Biology 2016 © Ashby Merson-Davies

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water vapour in air space in leaf

\·····..

.

cytoplasm xylem vessel transporting water from the roots

..

..

.

I 1' cohesive forces

1' adhesive forces

Carbohydrates

These include: •

•

•

•

sugars - monosaccharides and disaccharides,

glycogen, polysaccharides starch,

} cellulose

5 yH20H

14/0

�� C c1

�� �!oH cJ __ c2 I I

OH OH

D-ribose

6 CH20H

I c

5---o HYI ' H

14 H '-J1 C C

I'\. OH H / I HO '\. I 3 I/ OH

c---c2 I I H OH

alpha-D-glucose

The difference between alpha and beta glucose

Imagine the ring as lying horizontally. Note the position of the hydroxyl group -OH on carbon 1.

Simple diagram of leaf to show the role of cohesive and adhesive forces in transporting water

CH20H

I c---o 7/� "-?

H

C C

I'\. OH H /I HO'\. I I/ H

c---c I I H OH

beta-D-glucose

In alpha glucose it is below the ring and in beta glucose it is above the ring. In alpha glucose the hydroxyl groups are down, down, up, down - DOUD. In beta glucose the hydroxyl groups are up, down, up, down - UDUD.

Monosaccharides and disaccharides Key points � Monosaccharides have a single ring of carbon atoms. � Glucose and ribose are monosaccharides. � Ribose is a pentose because it has 5 carbon atoms. � Glucose is a hexose because it has 6 carbon atoms. � Two monosaccharide monomers (hexoses) are joined by condensation to form a disaccharide

- see page 25.'\..

Monosaccha"d;] Glucose Galactose Fructose Disaccharides

Two monosaccharides form a disaccharide / Maltose = glucose + glucose Lactose = glucose + galactose Sucrose = glucose + fructose

I/

IBSL Biology 2016 © Ashby Merson-Davies

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69. How many chromosomes 70. What is karyotyping? 71. What is the purpose of karyotyping?are there in each body cell of aperson with Down syndrome?

72. State two ways cells arecollected for karyotyping?

74. Identify these stages of the cellcycle.

73. What is non-disjunction?

Glossary

ASEPTATE A septum is a dividing wall: aseptate means without a septum. CONTRACTILE VACUOLE A special structure found in some simple fresh water organisms that collects the water entering the cell

via osmosis and then pumps it out of the cell. EXCRETION Removal of the waste products of metabolism. FACILITATE To make easier. GENOME In prokaryotes it is all the information in the single circular chromosome plus plasmids.

In eukaryotic animals it is all the information in a haploid set of chromosomes plus mitochondrial DNA. In eukaryotic plants it is all the information in a haploid set of chromosomes plus mitochondrial DNA plus chloroplast DNA.

HYDROPHILIC Water lovinq. HYDROPHOBIC Water hatinq. HYPERTONIC A solution that has a hiqher solute concentration than the one it is beinq compared with. HYPOTONIC A solution that has a lower solute concentration than the one it is beinq compared with. ISOTONIC A solution that has the same solute concentration as the one it is beina compared with. KINETIC ENERGY The enerqy an object possesses due to its motion. MESOSOME In prokaryotic cells the plasma membrane extends inwards to form a folded structure containing the

enzvmes for respiration. OS MOLARITY A measure of the concentration of osmotically active solutes in a solution. PARTIALLY PERMEABLE Some substances are able to diffuse throuqh the membrane. SECRETION Release from a cell by exocvtosis of a useful substance e.Q. hormone. SEM: TEM Scanninq electron microqraph : Transmission electron microqraph. SOLUTE A substance that dissolves in a solvent to form a solution. SOLVENT A liquid that dissolves a solute. WATER POTENTIAL The tendency of water to move from one region to another. The more dilute the solution the higher the

water potential.

Stem cell glossary

TOTIPOTENT Cells which can differentiate into all cell types because all their genes are functional. This can lead to development of a complete living organism.

PLURIPOTENT Cells which can differentiate into nearly all cell types and arise from totipotent cells as a result of some genes being switched off. This makes them valuable for stem cell therapy. Read about how adult cells can be turned into pluripotent cells - induced pluripotent cells - by following this link.

htti:1://stemcells. nih.gov/i nfo/basics/1:1ages/basics 1 O.as1:1x

MUL TIPOTENT Cells which can differentiate into a small range of closely related cell types. An example is haematopoietic stem cells (HSCs) found in bone marrow which can make every type of blood cell - red cells, white cells and platelets.

OLIGOPOTENT Cells which can only differentiate into a few cell types.

UNI POTENT Cells which can produce only one cell type, their own, but have the property of being able to keep dividing which distinguishes them from non-stem cells. An example would be the germinal epithelial cells in the testis.

86 IBSL Biology 2016 © Ashby Merson-Davies

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Self-Test Quiz

1. Which line in the table is correct?

Monosaccharide Disaccharide Polysaccharide

a. oalactose maltose

b. qlucose starch

C. fructose qalactose

d. glucose fructose

2. The four most frequently occurring elements in organisms are:

a. hydrogen, nitrogen, oxygen, sulphur,

b. carbon, hydrogen, oxygen, nitrogen,

c. carbon, nitrogen, oxygen, calcium,

d. carbon, nitrogen, hydrogen, sodium.

3. Hydrogen bonding is:

a. only found in water,

olvcooen

qalactose

starch

cellulose

b. an attraction between weak negative and positive charges,

c. a bond between hydrogen atoms,

d. formed during a condensation reaction.

4. Cohesion between water molecules means that:

a. water is a good solvent,

b. substances can diffuse in water,

c. osmosis can occur within a cell,

d. a transpiration stream can occur in plants.

5. Carbohydrates, lipids, proteins and nucleic acids all contain the elements:

a. nitrogen and oxygen,

b. carbon, hydrogen and nitrogen,

c. hydrogen, carbon and oxygen,

e. nitrogen, carbon and oxygen.

6. The term organic can be described as: a. the element carbon,b. a compound containing water,

c. a compound containing carbon,

d. a compound that dissolves in water.

7. Which one of the following represents the general structure of an amino acid?

H R 0 H

\ I I \ H R

I I N-c- CN-c - c

/ I '\ NH2CHRCOOH

b.

NH3CHRCOOH

C. / I '\

H H 0

a.

8. Which of the following represents the basic structure of the sugar ribose?

00

0 a. c.

H H 0

d.

b d.

IBSL Biology 2016 © Ashby Merson-Davies