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Lesson 1.1A

Introduction to Biology

Overview

Most knowledge about biological science has been acquired by carefully observing naturally occurring phenomena in living systems. These observations are compared with the data obtained from other relevant information. This process, well known as the

scientific method

, helps us explain phenomena.

The scientific method involves a series of steps that are always followed in the same order:

1. Answerable questions are created.

2. Predictions or hypotheses are made that are testable by

experiment

.

3. Experimental results are interpreted.

4. A

conclusion

or conclusions are made from interpretations, and new questions and predictions are often created.

In this lesson we will learn how to test a

hypothesis

by correctly conducting a systematic experiment.

• Inquiry Into Life

• Biology 12 Provincial Exam Preparation package

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Hypotheses must explain the scientist's observations, they must be testable, and they should help to predict future findings. Hypotheses often are composed of if-and-then statements for which only one variable is changed at a time. The variable that is deliberately changed is called the

independent variable

or manipulated variable. The observed variable that changes in response to the independent variable is called the

dependent variable

or responding variable.

For example, a simple hypothesis could be if a plant is left in a room with no light, then the plant will die.

A hypothesis:

1. must explain the observations

2. must be testable

3. should predict future findings

Observations

or experiments must be done to test a hypothesis. If an experiment does not support the hypothesis, the hypothesis is rejected and a new hypothesis is proposed or accepted. However, experimental data can not prove that a hypothesis is correct, only that it is supported in that particular case.

When conducting a systematic experiment, it is important that it be a

controlled experiment

. This means that all variables except the one being tested must remain constant. The group that remains constant is called the

control group

. An additional experiment is done in which the variable factor is introduced. This group is called the

experimental group

. Since all factors but one are constant, the scientist can determine if the one variable is responsible for the results.

For example, to look at the effects of placing a plant in an area with no light, the scientist would conduct an experiment with several plants of the same type. Each plant would be given the same amount of water and nutrients. The plant(s) in the control group would be placed in normal light conditions. The plants in the experimental group would be placed where in an area with no light. This method ensures that the amount light received by the plants is the only variable between the two groups.

The more often a hypothesis is tested and supported by the data, the more scientists trust its

validity

. When a hypothesis is tested several times and the data seems to support it, the hypothesis becomes a

theory

. A theory implies that the scientific community has confidence in the interpretation of a particular phenomenon. Using the example of the plants, a theory would be that plants require light to live.

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Experimental Design

Once an answerable question has been created, data or evidence must be collected. Scientists gather data by observation or experimentation. For the collected data to be considered valid, the observations must be repeatable when the experiment is performed under the same conditions. At some point in this process, a hypothesis (a tentative explanation or educated guess about a problem) can be made based on available evidence.

The following graph outlines the typical steps in the scientific method. Refer back to it as you continue reading through this lesson.

Question(I wonder)

Actual result does notsupport hypothesis

Actual result doessupport hypothesis

Actual result partiallysupports hypothesis

Hypothesis(possible explanation)

Reflect on results—Generate new questions

Observe (I notice)

Design andconduct experiment

Compare predictedresult to actual result

if

and

three possibleoutcomes

then...

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Lesson 1.3DComparison of Transport Mechanisms

OverviewIn the previous lessons you learned how cells are able to transfer molecules and nutrients into and out of the cell through the selectively permeable membrane.

In summary, there are two basic categories of transport through the membrane. Passive transport does not require chemical energy. Molecules move along a concentration gradient, from areas of higher concentration to areas of lower concentration. This method of transport includes diffusion (the movement of molecules), facilitated diffusion (the movement of a molecule with the help of a protein channel or carrier), and osmosis (the diffusion of water through a semi-permeable membrane).

The second category of transport requires energy from the cell because the movement of molecules goes against the concentration gradient. This method is called active transport.

In the guided practice you will construct a table to compare the various transport methods. You will compare and contrast the direction of movement, the conditions under which each occurs, and examples of each type of transport.

If possible, you should work through the Web site for this lesson.

• Biology 12 Web site http://www.openschool.bc.ca/courses/biology/bi12/mod1.html

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Section 2.1

DNA Replication

Section Overview

You’ve undoubtedly seen a few episodes of CSI and know the importance of DNA to crime scene investigations. Its importance is simple: each human being has a unique DNA blueprint so determining a DNA profile at a crime scene can help detectives determine suspects.

In Module 1 you briefly learned about DNA structure and function. In this section your knowledge of DNA structure and function will be taken further along with new information relating to RNA structure and function, DNA replication, and recombinant DNA (or cloning).

It bears repeating—each person has a unique DNA blueprint—you are a unique human being with unique physical and mental characteristics provided by your parents. You are special… just don’t get into trouble with the police!

PT

P

P

P

P

P

G

G

T

T

C

C

C

A

A

A

G

P

P

P

P

P

G

G

T

T

C

C

A

A

onenucleotide

Overview of DNA Structure

DNA Double

Helix

gene

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Lesson 2.2AProtein Synthesis, Part 1: Transcription

OverviewThe structure of the DNA molecule is the same in every living organism. All of life, in its infinite variety, from slime mould to the extinct Stegosaurus, is constructed from the same basic information contained in each cell. How is it possible that a molecule consisting of only six parts can provide all the information needed to produce millions of species of life?

You have already learned about the structure of DNA and that it is made up of a long series of nucleotides. These nucleotides are made up of a deoxyribose sugar, a phosphate group, and a nitrogenous base (A, T, C, or G)—the six parts of the DNA molecule. The bases are paired (A with T and C with G) and joined by hydrogen bonds, and the sugars and phosphate groups form the backbone of DNA’s three-dimensional double helix.

DNA codes for amino acids, which are the building blocks of proteins. Proteins, in turn, have a number of functions, including support, structure, movement, transport, communication, and immune defense. Protein-containing structures include hair, nails, hooves, horns, hormones, antibodies, blood proteins, and enzymes.

In the next two lessons you will investigate protein synthesis, the complex process of creating a protein from a DNA sequence. Two major processes are involved:

In this lesson you will learn about the process of transcription, and begin to focus on how the information contained in DNA is processed to form a final product—a protein.

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Enzymes and MetabolismBiochemical reactions are chemical reactions that occur in living organisms. These reactions begin with one or more reactants, and then convert these reactants to products. The many chemical reactions that occur in cells are collectively termed metabolism.

A typical chemical reaction might be described as:

A + B = C + D

where A and B are reactants, and C and D are products.

However, reactions in cells are often more complex and occur as part of a metabolic pathway—a series of conversions in which the product of one reaction becomes the reactant in the next reaction:

A B C D E F

Note that B, C, D, and E are both reactants and products. For example, in the reaction A B, A is the reactant and B is the product. Next, in B C, B becomes a reactant and C is a product, and so on.

Cellular metabolism must occur rapidly in order to sustain the life of an organism. This is why metabolic pathways, such as the one above, require enzymes. Enzymes are proteins that act as catalysts. They speed up chemical reactions without being used up in those reactions. The molecules that react with enzymes are called substrates (substrate is another word for reactant). Enzymes are specific—each enzyme will only form a complex with a certain substrate. That is why different enzymes are used in different steps of a metabolic pathway.

In your Inquiry Into Life textbook, read the information on metabolic pathways and enzymes before you proceed.

Enzyme 1 Enzyme 2 Enzyme 3

XW Y

Metabolic Pathway

Z

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Section 3.1

Digestive System

Section Overview

While you are eating a meal, many cellular activities occur to digest it. The focus of this section is to explore these cellular activities and how they cooperate within the organs of the digestive system. So, the next time you growl down that burger, you'll know what's going on in the body to help digest it.

tongue

mouth

epiglottis

liver

gall bladder

duodenum

smallintestine

appendix

rectum

stomach

pancreas

large intestine

anus

esophagus

cardiac sphincter

pyloricsphincter

pharynx

parotidsalivary gland

submandibularsalivary gland

sublingualsalivary gland

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Section 3.2Circulatory System

Section Overview

The circulatory system is responsible for transporting materials throughout the entire body. It transports nutrients, water, and oxygen to your billions of body cells and carries away wastes such as carbon dioxide that body cells produce. It is an amazing highway that travels through your entire body connecting all your body cells.

The main parts of the circulatory system are the heart, arteries, capillaries, and veins. Each of these parts is discussed in detail within this section. Additional topics include the lymphatic system and fetal circulation.

Did you know one drop of blood contains a half a drop of plasma, 5 MILLION red blood cells, 10 thousand white blood cells, and 250 thousand platelets?

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Heart AnatomyThe heart is a cone-shaped, fist-sized, muscular organ found within the thoracic cavity beneath the sternum and between the lungs. It is a double pump that pushes blood through the pulmonary and systemic circuits at the same time. The heart has four chambers—two atria and two ventricles. The right side of the heart pumps blood to the lungs via the pulmonary trunk, and the thicker walled left side of the heart pumps blood to the body via the aorta.

For an overview of the heart, see Figure 12.3 and 12.4 on pages 220–221 of your Inquiry Into Life textbook.

Contractions of the heart are synchronized so both atria contract to load the ventricles and then both ventricles contract to push blood into the pulmonary and systemic circuits. (Note: the septum dividing the two sides of the heart is muscle shared by both ventricles. During contraction, it provides force for both ventricles at the same time.)

anterior vena cava

pulmonary arteryto right lung

pulmonaryveins from right lung

aorta

rightatrium

rightventricle

left ventricle

leftatrium

posteriorvena cava

semilunarvalve

septum

atrioventricularvalve aorta to

lower body

aorta toupper body

pulmonaryveins fromleft lung

pulmonary arteryto left lung

pulmonary artery

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Lesson 4.2AUrinary System Anatomy

OverviewThe kidney is the main organ of excretion, which is the process of removing nitrogen wastes from the body. Nitrogen compounds, mainly ammonia, are produced during the breakdown of proteins. Ammonia is very toxic, so it is quickly combined with carbon dioxide to produce urea. If left to accumulate, the body would be overwhelmed within days and the major organs would stop functioning. As a result, the kidney is one of the body’s essential organs. People whose kidneys fail must submit to artificial removal of wastes by dialysis, or have their kidneys replaced with a donated kidney.

As well as excretion, the kidneys regulate water concentration and pH (acid/base balance.) Additionally, the kidneys also release hormones important in Na+ regulation (renin) and red blood cell production (erythropoietin).

• Inquiry Into Life

• Biology 12 Provincial Exam Preparation package

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The Urinary SystemThe urinary system consists of two kidneys (flattened fist-sized organs), the ureters that carry urine to the bladder (stores urine), and a single urethra, (carries urine out of the body). Study the provided diagram of the urinary system. You may want to cover the labels and practice naming the parts.

urethra

ureter

kidney

urinarybladder

renal vein

renal artery

aortainferiorvena cava

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Lesson 3.4AThe Anatomy of the Respiratory System

OverviewAt rest, the body moves 10 litres of air into and out of the lungs every minute. This movement of air into and out of the lungs is called breathing. The human lungs contain 300 million alveoli with a surface area forty times greater than that of the skin. The alveoli are responsible for the exchange of oxygen and carbon dioxide between the lungs and the blood. This lesson introduces the anatomy of the respiratory system and the functions of each individual organ.

• Inquiry Into Life

• Biology 12 Provincial Exam Preparation package

• Biology 12 Web site

http://www.openschool.bc.ca/courses/biology/bi12/mod3.html

The Anatomy of the Respiratory SystemThe respiratory system is responsible for the process of breathing, and it cooperates with the circulatory system in the process of respiration. Breathing involves the organs of the respiratory tract. These organs transport oxygen-rich air to the blood in the capillaries of the alveoli and remove carbon dioxide and water taken to the lungs from the tissues.

There are three types of respiration. External respiration exchanges oxygen and carbon dioxide in the alveoli of the lungs. Internal respiration is the exchange of gases between the capillaries and the tissue fluid. In cellular respiration, cells use oxygen to burn glucose to produce ATP energy and the waste products carbon dioxide and water.

Both the mechanism of breathing and external and internal respiration are discussed as separate lessons in this unit.

Resource List

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If you have access to the Internet, go to the Biology 12 Web site to check out further online resources.

Structure and Functions of the Respiratory SystemThe following diagram illustrates the structure and functions of the respiratory system. Refer also to Figure 15.1 on page 286 of your Inquiry Into Life textbook.

The Nasal Cavity — Air from outside the body passes through two nostrils or nares and into the nasal cavities. Ciliated cells in the upper parts of the nasal cavities are odour receptors and are responsible for the sense of smell.

Pharynx or Throat — The pharynx is a common passage way for both the respiratory and digestive systems.

nasal cavity

mouth

epiglottis

esophagus

trachea

bronchi

lungs

bronchiole

alveoli(air sacs)

diaphragm

larynx

rib

pharynx

thoracic cavity

pleuralmembranes

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Glossary:

action potential

the electrical potential determined by unequal ion distribution when a particular site on the neuron membrane is conducting an impulse; normally about +40 millivolts

active process

a biological process (e.g. action potential of neurons) that requires energy to make it occur

adrenal cortex

outer part of the adrenal gland located on the top of each kidney

afferent arteriole

blood vessel carrying blood to each glomerulus

aldosterone

hormone released from adrenal cortex; stimulates reabsorption of Na+ and water by distal tubule; responsible for maintaining blood volume (pressure)

all-or-none response

is the principle by which neurons either reach a stimulation threshold and fire or they don’t receive enough stimulation so don’t fire at all. It’s all-or-none in terms of a neuron firing or not

anterior pituitary

releases FSH and LH after being stimulated by hypothalamus and low concentrations of each (negative feedback)

anti-diuresis

decrease in urine output