WELCOME TO BIOLOGYMiss Tagore

Biology Lesson 1 – Learning Intentions

Understand why we study science.

Describe the stages of the scientific method.

Describe the standardised way of measuring mass, length and volume.

State that this system is called the metric system.

Why do we study science?

The word science comes from the Latin "scientia“, meaning knowledge.

Galileo before the Holy Office, a 19th century painting by Joseph-Nicolas Robert-Fleury

The scientific method 1. Observation and description of a phenomenon

or group of phenomena.

2. Formulation of an hypothesis to explain the phenomena.

3. Use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations.

4. Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments.

THE METRIC SYSTEM

Mass – What does it actually mean? Mass measures how much “stuff” there is

in an given area or volume.

Mass is measured in: grams (g) and; kilograms (kg).

Grams (g) to Kilograms (Kg)1000g = 1Kg500g = 0.5Kg100g = 0.1Kg10g = 0.01Kg1g = 0.001Kg

Volume The amount of 3-dimensional space an object

occupies. Capacity.

Metric units of volume are: cubic centimeters (cm3); cubic meters (m3) and; Liters (l) Volume

1cm3 1ml 0.001L

10cm3 10ml 0.01L

100cm3 100ml 0.1L

1000cm3 1000ml 1L

Length

Metric units of length are: milimeters (mm) centimeters

(cm) meters (m) Kilometers

(Km).1Kilometer (km) = 1,000 meters

(m)

1 meter (m) = 100 centimetres(cm)

1 centimetre(cm) = 10 milimeters (mm)

Making Metric Measurements

Lab Table Measurementsm cm mm

LengthWidthHeight

•Copy and complete the table below – you must always draw tables with a ruler!

•Using a meter stick, measure the dimensions of the table in meters.

•Once you have recorded these dimensions, convert them into centimeters and millimeters.

Making Metric Measurements

Test Tube Measurementscm mm

LengthDiameter of mouth

•Copy and complete the table below – you must always draw tables with a ruler!

•Using a ruler, measure the dimensions of the test tube in centimeters.

•Once you have recorded these dimensions, convert them into millimeters.

Making Metric Measurements

Measurement of Volume

mlWater in test tube

•Copy and complete the table below – you must always draw tables with a ruler!

•Collect a test tube and fill it right to the top.

•Using a measuring cylinder, carefully measure out the volume of water and record volume to the nearest millimeter.

Why Metric?

The metric system is used in science because

It is used by the whole world, America is the exception!

It is easier to work with numbers that are multiples of ten.

Converting between metric units For any two metric units, you convert from

the larger unit to the smaller by multiplying by one of 10, 100, 1000 etc.

The reverse is also true; you can convert from a smaller unit to a larger by dividing by one of 10, 100, 1000 etc.

Have a look at the following examples see how this works:

Litres and Millimetres

1 litre = 1000ml

1.68 litres = 1680ml

Units of Volume

x1000

÷1000

Units of Volume

Metres and Millimetres

1 m = 1000mm

2.6m = 2600mm

x1000

÷1000

Units of VolumeCentimetres and Millimetres

1 cm = 10mm

31.5cm = 315mm

x10

÷10

Kilometres and Meters

1 km = 1000m

0.75km = 750m

Units of Length

x1000

÷1000

Kilograms and Grams

1 kg = 1000g

3.5kg = 3500g

Units of Mass

x1000

÷1000

Over to you…

Collect a problem sheet on metric conversions and complete it to the best of your ability.

http://www.homeschoolmath.net/worksheets/measuring.php

The Light Microscope

Eye piece

Light source

Diaphragm

Lens

StageFocusing

wheel

Fine focus

Base

Practical task 1 – using a light microscope

Apparatus: Compound light microscope Microscope slide Cover slip Newspaper/magazine Dropper Water

Practical task 1 – using a light microscope1. Get into pairs or groups of three.

2. With your partner, prepare a slide each using the letter “e” that you have cut out.

3. Look at your slides under the microscope at the different powered lenses. Remember to start with the lowest magnification and work your way up.

4. Make a sketch of what you see at all magnifications. Make sure that you label your diagrams with the appropriate magnification.

Tips for drawing microscope specimens Draw a circle to represent the circle of light you see through

your microscope (called the field of view).

Under the circle, write the total magnification you are using to view the specimen.

Then draw what you see within that circle.

Make sure what you draw is in proportion to the circle. For example, if what you see only takes up half the space of the circle, don’t make it the full size of the circle in your drawing.

Do not draw all of the specimen if you can only see part of it.

Why the letter e? We use the letter e because it demonstrates

very clearly what a microscope does to the orientation of the specimen that you are looking at.

The image is reversed And The image is inverted.

Thus the entire image is both reversed and inverted

Practical task 2 – using a light microscope

Apparatus: Compound light microscope Microscope slide Cover slip Iodine solution Mounting needle Small section of onion skin

Practical task 2 – using a light microscope1. Get into pairs or groups of three.

2. With your partner, prepare a slide with a section of onion skin as demonstrated by your teacher.

3. Look at your slides under the microscope at the different powered lenses. Remember to start with the lowest magnification and work your way up.

4. Make a sketch of what you see at all magnifications. Make sure that you label your diagrams with the appropriate magnification.

5. Label the structures of the cell that you can see. You should be able to label at least three.

Points to consider Now that you have completed your practical, look at

your drawings at each magnification.

The cells that you can see in each diagram is known as the field of view (fov).

Consider the following questions:

1. Are the number of cells different in each fov? 2. If so, can you think of an explanation for this?3. Are you able to see all the structures of a plant cell?

Give a reason for your answer.4. The smallest units we have discussed so far are

millimetres. Are these units suitable for microscopy?

Structures that you see with a light microscope

Structures that you do not see but are actually there!

Units used in microscopy

The cells and their compounds like cell organelles are measured in terms of the fractions of a millimetre, because of their extremely small size.

The commonly used terminologies for these units are micrometres and nanometres

Micrometres(µm)

A micrometre or micron is one thousandth of a millimetre

1mm = 1000 µm

0.1mm = 100 µm

0.01mm = 10 µm

0.001mm = 1 µm

Nanometres(nm)

A nanometre or is one thousandth of a micrometre.

1µm = 1000 nm

0.1µm = 100 nm

0.01µm = 10 nm

0.001µm = 1 nm

Cell Structure and Function All living things are composed of

cells;

Cells are the basic units of structures and function in living things;

All cells come from preexisting cells.

Eukaryotic cells

Eukaryotic cells include both plant and animal cells.

They are referred to as eukaryotic because they contain membrane bound nuclei.

Prokaryotic Cells

Prokaryotic cells include bacteria and their relatives.

These are usually unicellular organisms.

They are referred to as prokaryotic because they do not contain a membrane bound nucleus.

Cell Structures

Golgi apparatus:

Packages and secretes complex molecules.

Cell Structures

Secretory vesicles:

Move to the surface of a cell and discharge their contents

Cell Structures

Mitochondria:

Site of aerobic respiration.

Cell Structures

Chloroplasts:

Site of photosynthesis.

Cell Structures

Smooth endoplasmic reticulum:

Large surface area for transport of lipids.

Cell Structures

Rough Endoplasmic Reticulum (Rough E.R.)

Large surface area for transport of proteins.

Cell Structures

Ribosomes:

Site of protein synthesis.

Cell Structures

Nucleus:

Controls cell activities. Contains DNA and mRNA.

Nuclear envelope

Nucleolus

Nuclear pore

Cell Structures

Centrioles:

Involved in spindle fibre formation in meiosis/mitosis

Cell Structures

Lysosomes

Contains powerful enzymes which digest redundant structures.

Cell Structures

Cytoplasm:

Fluid in which many chemical reactions take place.