BIOLOGY

CLASSIFICATION : TEACHER”s NOTES

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Bionomial Nomenclature
Rules for Naming Organisms

All scientific names must have 2 Latin words.

Two different types of organisms can not have the same scientific name.

The first letter of the genus name is capitalized; the first letter of the species name is lowercase.

Scientific names are italicized or underlined.

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.

What is the Dichotomous Key?

The Dichotomous Key is a tool that scientists use to determine the classification of living things in the
natural world - from trees to animals to fungus. It's usually presented in the form of a flowchart, giving
you two options on each branch to help make the identification process easier. Construct one as shown
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2.1 Concept and use of a classification system

1 Understand that organisms can be classified into groups by the features they share

2 Describe a species as a group of organisms that can reproduce to produce fertile

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5.48.34-PM.png

3 Describe the binomial system of naming species as an internationally agreed system in which the

scientific name of an organism is made up of two parts showing the genus and species

4 Construct and use dichotomous keys based on identifiable features

2.2 Features of organisms

1 State the main features used to place all organisms into one of the five kingdoms: Animal, Plant,
Fungus, Prokaryote, Protoctist

2 State the main features used to place organisms into groups within the animal kingdom, limited to:

(a) the main groups of vertebrates: mammals, birds, reptiles, amphibians, fish

(b) the main groups of arthropods: myriapods, insects, arachnids, crustaceans

3 State the main features used to place organisms into groups within the plant kingdom, limited to ferns

and flowering plants (dicotyledons and monocotyledons)

4 Classify organisms using the features identified in 2.2.1, 2.2.2 and 2.2.3

5 State the main features of viruses, limited to protein coat and genetic material Understand that
viruses can only replicate in living cells
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Monera

This group includes all kinds of bacteria, having a prokaryotic cell

The cell does not contain a nucleus

There are different shapes of bacteria present; spherical- cocci, rod-shaped-

bacillus, comma- vibrio and spiral- spirilla
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They mainly reproduce by fission, spore formation under unfavourable
conditions and also by DNA transfer from one bacterium cell to another

Protista

The group includes unicellular eukaryotes

A photosynthetic protist is a link between plants and animals

They contain a well-defined nucleus and other membrane-bound cell organelles

They include protozoan, slime moulds

, Fungi

Fungi are cosmopolitan and found everywhere

They are heterotrophic and get the nutrients by absorption

Their cell wall is made up of chitin or fungal cellulose

Their mode of nutrition is saprophytic, parasitic or symbiotic and the main food
reserve is glycogen

Vegetative reproduction is by fragmentation, budding or fission

Asexual reproduction is by spores and sexual reproduction by gamete

formation.

Plantae

Mostly autotrophic, chlorophyll-containing, eukaryotic organisms

Characterised by the presence of rigid cell wall made up of cellulose

Some plants are partially heterotrophic such as Insectivorous (Venus flytrap,

Bladderwort) and parasites (Cuscuta)

Kingdom Plantae includes Algae, Bryophytes, Pteridophytes, Gymnosperms and

Angiosperms
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5. Animalia

All the heterotrophic, eukaryotic and multicellular organisms are included in

the Kingdom Animalia. They lack a cell wall.
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Invertebrate animals are those that do not have a backbone. The majority of the world's animals are
found in this group, representing 95% of the existing species. Being the most diverse group within this
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kingdom, its categorization has become very difficult.
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VERTEBRATES
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There are 4 Concepts of Cell Theory (Definition)

Basic Structure and functional units of life

All activities for life occur in cells

Human body contains 3 trillions of cells

Biochemical activities of a cell are dictated by their organelles

The Structure of The Cell

CELLS VARY GREATLY IN SIZE , SHAPE AND FUNCTIONS

ALL CELLS ARE COMPOSED OF PRIMARILY CARBON , HYDROGEN,

NITROGEN AND OXYGEN

All cells have same basic parts and some common functions

A generalized human cell contains the plasma membrane , the

cytoplasm, and the nucleus
The Plasma Membrane :

The Cytoplasm

Nucleus
Organelles(Organelles or a cell organs. Specialized part of a cell having some specific function)

1.Plasma membrane
Is a double layer of phospholipids, cholesterol and proteins and encloses the cell as outer layer :
Selective permeab Plasma membrane is selectively permeable barriers

Passive process

Diffusion

Osmosis

filtration

Active process

Use energy to transport (ATP)

Use solute pumps

2.Cytoplasm/Cytosol
It is a clear substance that consists of all of the contents outside of the nucleus of a cell

The cytoplasm/cytosol or intracellular fluid (ICF) or cytoplasmic matrix is the liquid found inside cells.

Organelles or a cell organs. Specialized part of a cell having some specific function;

Different in Size shape and function

All Cells are composed primarily of Carbon, Hydrogen and Nitrogen and Oxygen

All Cells have the same basic parts and some common functions

Typical cell has: plasma membrane , cytoplasm , cytosol, organelles and nucleus

3 .Nucleus
It contains the majority of the cell's genetic material in the form of multiple linear DNA molecules
organized into structures called chromosomes. Nucleus

Almost all Cells have Nucleus : These are spherical bodies found inside the cytoplasm
Most cells have only one nucleus, but some like the skeletal muscles have more than one

Cells without nucleus : matured erythrocytes RBCs

A Nucleus is the largest organelle in the cell the controlling center of the cell

Nucleus contains the body’s genetic material which directs all metabolic activities of the body (46
Chromosomes in Humans) made up of Deoxyribonucleic acid DNA a fine network of thread called
chromatins

ORGANELLES
Nucleus is also an organelle which is done above.

1 Mitochondria ( Power house )

Shaped like sausage they are found in the cytoplasm

They are responsible for the energy of the cell:

They are responsible for aerobic respiration which produces chemical energy i.e. ATP

2.Endoplasmic Reticulum ER

ER: series of canals in the cytoplasm. Mainly Transport System of the cell. - 2 types

i)Smooth ii)Rough

Smooth -ER synthesizes Fatty acids & Steroids and detoxify some drugs

Rough ER –synthesizes enzymes and hormones outside the cell

3.Golgi Apparatus

Are flat membranous sacs

Package proteins from ER to form secretory granules

Packages Digestive Enzymes into lysosomes

4. Ribosomes

No membrane

Most numerous organelle

Made in nucleus (specifically in nucleolus)

Function

Aids in protein synthesis

Free ribosomes make proteins used by the cell

Ribosomes on rER make proteins for export to other cells

CHAPTER 1 CELLs
Examine under the microscope, animal cells and plant cells from any suitable locally available material,

using an appropriate temporary staining technique, such as methylene blue or iodine solution.Taking
sample of cheek cells as animal cells.
Specialized Cell:Animal Cell examples:
Red Blood cells: anucleate, more room for hemoglobin thus more room for O2 molecules

Muscle cells: multinucleate, more mitochondria to produce more ATP needed for movement, have
contractile fibers

Epithelial cells: skin cells modified to be a waterproof barrier for organisms

Plant Cell Examples:

Root hair cells:A long extension in soil increasing its surface area modified for absorbtion of water

Stem cells: modified to include vascular tissues as Xylem Vessel s to distribute water and Phloem (Seive
tubes)to transport glucose and aminoacids.

Leaf cells: Extra chloroplasts for photosynthesis and storage areas for gas exchange with environment

Why would our bodies evolve 220 different types of cells?

3 What is a Specialized Cell?

A cell that has a particular structure and performs a specific function

Each type has unique shape, size and features allowing it to do its job accurately

4 The cells in animals are not all identical.

They perform specific functions, such as delivering oxygen and fighting disease, moving the skeleton,
storing energy or coordinating the whole body.

5 Plant cells also have a variety of specialized cells

Plant cells also have a variety of specialized cells. Cells in the leaf of a tree have a different structure and
function from the cells in the trunk.

A cell is the smallest unit of living matter; thebasic unit of life.

Some kinds of organisms, like bacteria, are made of only one cell.

Other types of organisms, like people and trees are made up of trillions of cells.

How are organisms organized? Many-celled organisms are organized in cells, tissues, organs, and
organ systems Cells:

Animals and plants are many-celled organisms.

Animals are made up of many kinds of cells.

You are made of blood cells, bone cells, skin cells, and many others.

A plant also has different cells in its roots, stems, and leaves. Tissues:

In your body, a single skin cell or blood cell does not work alone.

Cells work together in groups called tissues.

A tissue is a group of similar cells that work together carrying out a certain job.

For example, skin cells work together as skin tissue that covers and protects your body. Other kinds of
tissue in an animal’s body include muscle, bone, nerve and blood.

Plant cells are also organized into tissues.

For example, leaves of plants are made of tissues that help the plant make food.

Organs Throughout your body, tissues are grouped together so they can work together.
An organ is a group of tissues that work together doing certain jobs.

Roots, stems, and leaves are organs of a plant.

A leaf is an organ that makes food for the plant.

The roots of a plant are the main organ in the root system of a plant.

The heart, lungs, and brain are examples of animal organs.

Your heart is an organ:

It contains muscle tissue, nerve tissue, and blood tissue.

Its job is to pump blood throughout your body.

Organ Systems :Organ systems work together so life processes like breathing and digestion can
be carried out, keeping many-celled organisms, like you, healthy and alive.

When a group of parts work together, they form a system.

A group of organs working together to carry out a specific life function is called an organ system.

A plant’s roots, stem, and leaves are an organ system.

Your digestive system is an organ system:

It contains your mouth, esophagus, stomach, small and large intestines, and liver.

Digestion breaks down food and absorbs nutrients you need to live.

Cells, Tissues, Organs, and Systems

A cell is the smallest unit of living matter; the building blocks of living things.

Tissues are groups of cells working together to perform a certain job.

Organs are groups of tissues that perform a certain function.

Organs working together to carry out a certain life function are an organ system.
are made up of trillions of cells.
BIOLOGY : ENZYMES

ENZYMES TEACHER’S NOTES

An enzyme is a substance that acts as a catalyst in living organisms, regulating the rate at which
chemical reactions proceed without itself being altered in the process. The biological processes that
occur within all living organisms are chemical reactions, and most are regulated by enzymes.

1 Enzymes The PROTEIN catalyst of life

2 Enzymes…. are protein substances that are necessary for: 1. The chemical reactions that occur in your
body. Ex. Pepsin (enzyme) breaks protein down in the stomach. 2. Help to release energy in the form of
ATP (adenine tri-phosphate) to the cells

3. Chemical Reactions Reactants- things that start the reaction (what goes in). Products- things that are
produced (what comes out).

4 I. Enzyme Vocabulary A. Enzymes end in –

use it is not altered, can do same thing over, and,

Site where enzyme binds to substrate E.

strong acids or bases

6 II. How Do Enzymes Work? DEMO 1. The enzyme has an active site which has a on its surface which
has a very specific shape. 2. The enzyme and the substrate (what enzymes acts upon) temporarily join
together forming the enzyme substrate complex.

7 III. Importance of Enzyme Shape A. Enzymes have specific shapes B. This means enzymes are specific
to their substrate C. They will only attach to a substrate that “fits” their shape D. If shape of enzyme is
denatured, will it be able to bind to its substrate? NO! E. Two things can cause denaturing: 1.
Temperature 2. pH

8 IV. Enzyme-Substrate Complex A. Formed when enzyme binds to substrate B. Very specific

9 C. Lock and Key Model 1.Enzyme-substrate complex often compared to a lock and key. 2. Active site
on enzyme can only “FIT” or bind to a specific substrate Example: Amylase will bind to starch, but not
cellulose

10 Enzyme-Substrate (ES) Complex (lock and key model) http://highered.mcgraw-

hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html Enzyme is
unchanged
12 Bellwork – do this in your journal Tape the Lock and Key Model illustrating an enzyme into your
-
reaction an example of digestion or synthesis? How can you tell?

13 Substrate Enzyme Substrate Products Digestion b/c there are 2 smaller products formed Active Site

14 V. What factors influence Enzyme Action? A. Remember, enzymes speed up reactions B. What can
affect the rate at which enzymes perform? 1. It’s shape! a. Denaturing affects rate C. The amount of
enzyme and substrate!

15 1.Temperature - Enzyme shape and reaction rate: a. Enzymes have a specific temperature range at

cause enzymes to denature c. Shape is altered, so reaction rates are SLOWED or stopped altogether

16 d. Reaction rates will DROP dramatically depending on how much denaturing of enzyme Temperature
vs. Reaction Rate

17 . pH - Enzyme shape and reaction rate: a. Enzymes have a specific pH range at which they work best i.
EX. Most enzymes work best at pH 7 ii. Where in the body would enzymes be optimal at a low (acidic)
pH? Why? i. In stomach, this is because stomach acid has a low pH b. pH not in the optimal range will
cause enzymes to denature c. Shape is altered, so reaction rates are SLOWED or stopped altogether

18 . Reaction rates will DROP dramatically depending on how much denaturing of enzyme. stomach
Small intestine pH vs. Reaction Rate

19 . Concentration - Enzyme amount and reaction rate: a. Enzyme rate also depends on the amount of
enzyme and substrate b. Little enzyme, lots of substrate: i. Slower rates ii. How can we speed up the
rate? 1. Add more enzyme until max. rate achieved. Substrate Concentration vs. Reaction Rate

20 Step 1 – molecule A (enzyme) is combining with molecule B (substrate) Step 2 – enzyme-substrate

complex is formed (where digestion will begin) Step 3 - reaction completed and molecules break away;
enzyme is unchanged and is able to repeat the process many times again. 35) reaction is digestion
(molecule B was broken apart) 36) heating speeds up the reaction BUT excess heat causes the enzyme
to denature thereby slowing down or stopping the reaction all together 37) 338) 239) 2 40) No digestion
occurred b/c the enzymes are specific (the enzyme present was for protein NOT starch)
Enzyme Investigations

Amylase is an enzyme that digests starch (a polysaccharide of glucose) into maltose (a disaccharide of
glucose).

Starch can be tested for easily using iodine solution.

 Investigating the Effect of Temperature on Amylase

Starch solution is heated to a set temperature

Iodine is added to wells of a spotting tile

Amylase is added to the starch solution and mixed well

Every minute, droplets of solution are added to a new well of iodine solution

This is continued until the iodine stops turning blue-black (this means there is no more starch
left in the solution as the amylase has broken it all down)

Time taken for the reaction to be completed is recorded

Experiment is repeated at different temperatures

The quicker the reaction is completed, the faster the enzyme is working
 Investigating the Effect of pH on Amylase Activity

Place single drops of iodine solution in rows on the tile

Label a test tube with the pH to be tested

Use the syringe to place 2cm3 of amylase in the test tube

Add 1cm3 of buffer solution to the test tube using a syringe

Use another test tube to add 2cm3 of starch solution to the amylase and buffer solution, start the
stopwatch whilst mixing using a pipette

After 10 seconds, use a pipette to place one drop of mixture on the first drop of iodine, which should
turn blue-black

Wait another 10 seconds and place another drop of mixture on the second drop of iodine

Repeat every 10 seconds until iodine solution remains orange-brown

Repeat experiment at different pH values – the less time the iodine solution takes to remain orange-
brown, the quicker all the starch has been digested and so the better the enzyme works at that pH
BIOLOGY MOVEMENT OF MOLECULES
TEACHER’s NOTES
 The molecules of a gas such as oxygen are moving about all the time. So are the molecules of a
liquid or a substance such as sugar dissolved in water. As a result of this movement, the molecules
spread themselves out evenly to fill all the available space. So diffusion happens in all phases of matter.
The diffusion of solutes across a membrane. Each of the large arrows under the diagrams shows the net
diffusion of the dye molecules of that colour.

Each dye molecule wanders randomly, but there will be a net movement of the dye molecules
across the membrane to the side that began as pure water. The dye molecules will continue to
spread across the membrane until both solutions have equal concentrations of the dye. Once
that point is reached, there will be a dynamic equilibrium, with as many dye molecules crossing
the membrane each second in one direction as in the other.

We can now state a simple rule of diffusion: In the absence of other forces, a substance will
diffuse from where it is more concentrated to where it is less concentrated. Put another way,
any substance will diffuse down its concentration gradient . No work must be done to make this
happen; diffusion is a spontaneous process. Note that each substance diffuses down its own
concentration gradient, unaffected by the concentration differences of other substances.

Much of the traffic across cell membranes occurs by diffusion. When a substance is more
concentrated on one side of a membrane than on the other, there is a tendency for the
substance to diffuse across the membrane down its concentration gradient (assuming that the
membrane is permeable to that substance). One important example is the uptake of oxygen by
a cell performing cellular respiration. Dissolved oxygen diffuses into the cell across the plasma
membrane. As long as cellular respiration consumes the O2 as it enters, diffusion into the cell
will continue, because the concentration gradient favors movement in that direction.

The diffusion of a substance across a biological membrane is called passive transport because
the cell does not have to expend energy to make it happen. The concentration gradient itself
represents potential energy and drives diffusion. Remember, however, that membranes are
selectively permeable and therefore have different effects on the rates of diffusion of various
molecules. In the case of water, aquaporins allow water to diffuse very rapidly across the
membranes of certain cells. The movement of water across the plasma membrane has
important consequences for cells.
Osmosis.
Two sugar solutions of different concentrations are separated by a selectively permeable membrane,
which the solvent (water) can pass through but the solute (sugar) cannot. Water molecules move
randomly and may cross through the pores in either direction, but overall, water diffuses from the
solution with less concentrated solute to that with more concentrated solute. This transport of water, or
osmosis, eventually equalizes the sugar concentrations on both sides of the membrane.
It seems logical that the solution with the higher concentration of solute would have the lower
concentration of water and that water would diffuse into it from the other side for that reason.
However, for a dilute solution like most biological fluids, solutes do not affect the water concentration
significantly. Instead, tight clustering of water molecules around the hydrophilic solute molecules makes
some of the water unavailable to cross the membrane. It is the difference in free water concentration
that is imporant. But the effect is the same: Water
diffuses across the membrane
from the region of lower solute concentration to that of higher solute
concentration until the solute concentrations on both sides of the
membrane are equal. The diffusion of water across a selectively
permeable membrane is called osmosis. The movement of water across cell
membranes and the balance of water between the cell and its environment are crucial to organisms.
Let’s now apply to living cells what we have learned about osmosis in artificial systems.

When considering the behaviour of a cell in a solution, both solute concentration and membrane
permeability must be considered. Both factors are taken into account in the concept of tonicity , the
ability of a solution to cause a cell to gain or lose water. The tonicity of a solution depends in part on its
concentration of solutes that cannot cross the membrane (nonpenetrating solutes), relative to that in
the cell itself. If there are more nonpenetrating solutes in the surrounding solution, water will tend to
leave the cell, and vice versa.

If a cell without a wall, such as an animal cell, is immersed in an environment that is isotonic to the cell
(iso means “same”), there will be no net movement of water across the plasma membrane. Water flows
across the membrane, but at the same rate in both directions. In an isotonic environment, the volume of
an animal cell is stable

The water balance of living cells. How living cells react to changes in the solute concentration of their
environment depends on whether or not they have cell walls. (a) Animal cells such as this red blood cell
do not have cell walls. (b) Plant cells do. (Arrows indicate net water movement since the cells were first
placed in these solutions.)

Now let’s transfer the cell to a solution that is hypertonic to the cell (hyper means “more,” in this
case more nonpenetrating solutes). The cell will lose water to its environment, shrivel, and probably die.
This is one reason why an increase in the salinity (saltiness) of a lake can kill the animals there—if the
lake water becomes hypertonic to the animals’ cells, the cells might shrivel and die. However, taking up
too much water can be just as hazardous to an animal cell as losing water. If we place the cell in a
solution that is hypotonic to the cell (hypo means “less”), water will enter the cell faster than it leaves,
and the cell will swell and lyse (burst) like an overfilled water balloon.

The cells of plants, prokaryotes, fungi, and some protists have walls. When such a cell is immersed in a
hypotonic solution—bathed in rainwater, for example—the wall helps maintain the cell’s water balance.
Consider a plant cell. Like an animal cell, the plant cell swells as water enters by osmosis. However, the
elastic wall will expand only so much before it exerts a back pressure on the cell that opposes further
water uptake. At this point, the cell is turgid (very firm), which is the healthy state for most plant cells.
Plants that are not woody, such as most houseplants, depend for mechanical support on cells kept
turgid by a surrounding hypotonic solution. If a plant’s cells and their surroundings are isotonic,
there is no net tendency for water to enter, and the cells become flaccid (limp).

However, a wall is of no advantage if the cell is immersed in a hypertonic environment. In this case, a
plant cell, like an animal cell, will lose water to its surroundings and shrink. As the plant cell shrivels, its
plasma membrane pulls away from the wall. This phenomenon, called plasmolysis, causes the
plant to wilt and can be lethal. The walled cells of bacteria and fungi also plasmolyze in
hypertonic environments.
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