Chapter 1 Themes in the Study of Life. What is Biology?

Chapter 1Themes in the Study of Life

What is Biology?

What is Biology?◦Scientific study of Life◦Filled with QUESTIONS

Good Questions Questions that can be investigated

What is Life?

What is Life?

7 Properties of Life

What is Life?

7 Properties of Life◦Order◦Evolutionary adaptation◦Responding to the environment◦Growth and development◦Reproduction◦Energy processing◦Regulation

What are the Major Themes of Biology

Major Themes of Biology◦New properties emerge at each level in the

biological hierarchy◦Organisms interact with their environments,

exchanging matter and energy◦Structure and function are correlated at all

levels of biological organization◦Cells are an organism’s basic units of

structure and functions◦The continuity of life is based on heritable

information in the form of DNA◦Feedback mechanisms regulate biological

systems

Evolution“Nothing makes sense except in the light of evolution”

- Who Said This?


Dobzhansky


Dobzhansky

Core Theme◦Evolution accounts for the unity and

diversity of life◦Its importance will demonstrate a large

role in this course Can always refer to Section 1.2 throughout

the semester

How do scientists pose and answer questions about the natural world?

How is Biology examined?


Reductionist approach Holistic approach Systems biology


Reductionist approach


Reductionist approach Reduce complex systems to simple components



Holistic approach



Holistic approach Larger-scale, with the objective of understanding how the emergent properties work together




Systems biology




Systems biology Goal is to construct models for the behavior of a whole systems

What is inquiry?

What is inquiry? Inquiry is the search for information and

explanation that often focuses on specific questions

Scientists use two main forms of scientific inquiry

Discovery ScienceHypothesis-Based Science


Discovery Science


Discovery Science Describing nature More qualitative in nature Can have quantitative aspects Describes natural processes Uses observation to gather information

(directly or indirectly) with tools Recorded observations are called data


Hypothesis-Based Science


Hypothesis-Based Science Describing nature More qualitative in nature Can have quantitative aspects Describes natural processes Uses observation to gather information

(directly or indirectly) with tools Recorded observations are called data

What is a hypothesis?

What is a hypothesis?Tentative answer to a well-

framed question◦Explanation on trial

Educated Guess that is based on experience and the data available from Observation

What makes a Good Hypothesis?

What makes a Good Hypothesis?TestableFalsifiableCannot be PROVENGains credibility by surviving attempts to falsify it

What makes a Good Hypothesis?Testable

What makes a Good Hypothesis?Testable A way to check the validity


Falsifiable


Falsifiable There must be some observation or experiment that could reveal if such an idea is NOT true

Generally, scientists frame two or more alternative hypotheses and design experiments to falsify




Cannot be PROVEN




Cannot be PROVEN Testing supports a hypothesis not by Proving it, but instead by not eliminating it through the falsification

It’s impossible to test ALL alternative hypothesis




Cannot be PROVEN Testing supports a hypothesis not by Proving it, but instead by not eliminating it through the falsification

It’s impossible to test ALL alternative hypothesis

Gains credibility by surviving attempts to falsify it

What are the Types of Data?

Types of DataQualitativeQuantitative

Types of DataQualitative


Recorded descriptions rather than numerical General observations Colors



Quantitative



Quantitative Recorded measurements Numerical in nature

What are theTypes of Reasoning

Types of Reasoning

Inductive ReasoningDeductive Reasoning

Types of Reasoning

Inductive Reasoning

Types of ReasoningInductive Reasoning

From induction Derive generalizations from a large number of

specific observations Ex:

If every organisms that you have studied is made of cells, then it would be acceptable to induce that all organisms are made of cells.

Types of Reasoning

Inductive Reasoning From induction Derive generalizations from a large number of

specific observations Ex:


Deductive Reasoning

Types of Reasoning

Inductive Reasoning From induction Derive generalizations from a large number of specific

observations Ex:


Deductive Reasoning Logic flows from general to specific Usually take the form of prediction of experimental or

observational results Ex:

If all organisms are made of cells, and humans are organisms, then humans are composed of cells

Scientific Method◦Ask a Question◦Do Background Research◦Construct a Hypothesis◦Test Your Hypothesis by Doing an

Experiment◦Analyze Your Data and Draw a

Conclusion◦Communicate Your Results

What is Experimental Design?

INTEGRATING EXPERIMENTAL DESIGN INTO

SCIENCE

Experimental Design: The ProcessPaper airplane - everybody builds

oneObserve the plane’s flight

◦Ready, set, hold it …◦How do we determine which is best?

5 minutes to modify, make one change

Write your hypothesis on your plane

Leading QuestionsHow did you act on your plane?What did you purposefully

change about your plane?How did you determine your

plane’s response?What remained the same

about about your plane?

Action PurposefulChange

ResponseTo Change

RemainedThe Same

Experimental Design DiagramTitle: The effect of ...IV... on ...DV...

Hypothesis: If the ...IV... is modified in this way,then this will happen to the ...DV...

Independent variable:

these boxesshow how theIV is modified

_____trials _____trials _____trials _____trials _____trials

Dependent Variable:

Constants:

Control:

Experimental Design Problems Compost & Bean Plants

After studying about recycling, members of John's biology class investigated the effect of various recycled products on plant growth. John's lab group compared the effect of different aged grass compost on bean plants. Because decomposition is necessary for release of nutrients, the group hypothesized that older grass compost would produce taller bean plants Three flats of bean plants (25 plantslflat) were grown for 5 days. The plants were then fertilized as follows: (a) Flat A: 450 g of three-month-old compost, (b) Flat B: 450 g of six-month-old compost, and (c) Flat C: 0 g compost. The plants received the same amount of sunlight and water each day At the end of 30 days the group recorded the height of the plants (cm).

Experimental Design Diagram

Title: The effect of different aged compost on beanplant growth.

Hypothesis: If older compost is applied, then plantgrowth will be increased.

Independent variable: Age of Compost

these boxesshow how theIV is modified

3 month oldcompost

6 month oldcompost No compost

# trials 25 trials 25 trials 25 trials

Dependent Variable: Height of plants (cm)

Constants: amount of light, water, compost

Control: no compost

Scenario 2 Metals & Rusting Iron

In chemistry class, Allen determined the effectiveness of various metals in releasing hydrogen gas from hydrochloric acid. Several weeks later, Allen read that a utilities company was burying lead next to iron pipes to prevent rusting Allen hypothesized that less rusting would occur with the more active metals. He placed the following into separate beakers of water: (a) 1 iron nail, (b) 1 iron nail wrapped with an aluminum strip, (c) 1 iron nail wrapped with a magnesium strip, (d) 1 iron nail wrapped with a lead strip. He used the same amount of water, equal amounts (mass) of the metals and the same type of iron nails. At the end of 5 days, he rated the amount of rusting as small, moderate, or large. He also recorded the color of the water.


Title: The effectiveness of various metals in preventing the rusting of iron.

Hypothesis: I f the chemical activity of the metallic wrapper is increased, then less rusting of iron will occur.

Independent variable: Type of metal wrapping strip these boxes show how the IV is modified

Iron nail with no metal

Iron nail with magnesium

Iron nail with aluminum

Iron nail with lead

# trials 1 trial 1 trial 1 trial 1 trial

Dependent Variable: amount of rusting , color of water

Constants: amount of water, mass of metal, type of nail

Control: nail with no metal

Perfumes & Bee's Behavior JoAnna read that certain perfume esters would agitate bees.

Because perfume formulas are secret, she decided to determine if the unknown Ester X was present in four different perfumes by observing the bees' behavior. She placed a saucer containing 10 ml of the first perfume 3 m from the hive. She recorded the time required for the bees to emerge and made observations on their behavior. After a 30-minute recovery period, she tested the second, third, and fourth perfumes. All experiments were conducted on the same day when the weather conditions were similar, e.g., air, temperature and wind.

Experimental Design DiagramTitle: The effect of various perfumes on the behavior of bees.

Hypothesis: I f the perfume contains Ester X, then the bees will display agitated behavior.

Independent variable: Type of perfume these boxes show how the IV is modified

Perfume 1 Perfume 2 Perfume 3 Perfume 4

# trials 1 trial 1 trial 1 trial 1 trial

Dependent Variable: time to emerge , behavior of bees

Constants: amount of perfume, weather, distance from hive

Control:

Fossils and Cliff DepthSusan observed that different kinds and

amounts of fossils were preset in a cliff behind her house. She wondered why changes in fossils content occurred from the top to the bank. She marked the bank at five positions: 5,10,15, 20, and 25m from the surface. She removed 1 bucket of soil from each of the positions and determined the kind and number of fossils in each sample.

Experimental Design DiagramTitle: The effect of depth on the different

types and amounts of fossils.Hypothesis: If depth increases in a fossil bank,

then different fossils will occur.Independent Variable: Depth of soil

Modifications 5 10 15 20 25

# of Trials 1 1 1 1 1

Dependent Variable: Amount and type of fossils.

Constant: 1 bucketControl ?

Aloe vera and Planaria Jackie read that Aloe vera promoted healing of burned

tissue. She decided to investigate the effect of varying amounts of aloe vera and regeneration of planaria. She bisected the planaria to obtain 10 parts (5 heads and 5 tails) for each experimental group. She applied concentrations of 0%, 10%, 20%, and 30% Aloe vera to the groups. Fifteen ml of Aloe vera solutions were applied. All planaria were maintained in a growth chamber with identical food, temperature, and humidity. On day 15, Jackie observed the regeneration of the planaria parts and categorized deeloped as full, partial, or none.


Title: The effect of aloe vera on regeneration of planaria.

Hypothesis: If more aloe vera is used then there will be an increased amount of aloe vera.

Independent Variable: Percentage of Aloe VeraModifications 10% 20% 30%

# of Trials 10 10 10

Dependent Variable: amount of regeneration

Constant: food, temperature, humidity

Control : 0% aloe vera

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Chapter 1 Themes in the Study of Life. What is Biology?