An introduction to biology with a focus on the unity and diversity of life.

An introduction to biology with a focus on the unity

and diversity of life

Learning goalsYou should understand:-What science is and how scientific knowledge is generated-What biology is and at what scales biologists study life-The diversity and unity of life-What one concept explains both the unity and diversity of life?

What is nature?

It is very natural for humans to try to know and explain nature (to inquire about nature)

How would you explain this?

Scientists try to describe and understand the natural world.

Scientists try to describe and understand the natural world.

How?

Science is a systematic way of knowing and understanding nature.

There are two main forms of inquiry•Discovery (or descriptive) science- Describing nature through observations and then analysis of data.

•Hypothesis-based science- Explaining nature by testing hypotheses (tentative answers to questions).

Hypothesis-based science typically uses the scientific method….

1.) Make an observation of something in nature. 2.) Frame a question that relates to your observations.3.) Propose a testable and falsifiable hypothesis (an answer to your question).4.) Using the hypothesis, make predictions.5.) Devise a way to test your prediction.6.) Assess results (do they support or refute your hypothesis).7.) Make conclusions.7.) Report all results and conclusions to the scientific community.



Did you prove your hypothesis about the lamp?



Did you prove your hypothesis about the lamp?

No, it would be impossible to test all alternative hypotheses (you did not reject it).

The nature of science

•Science is a systematic way of understanding nature.•Scientific knowledge changes.•Science does not produce “truths”. However, science produces theories.

A theory is broad in scope. It helps us make predictions about other phenomena. It is supported by a large body of evidence.

The nature of science

•Science is a systematic way of understanding nature.•Scientific knowledge changes.•Science does not produce “truths”. However, science produces theories.

A theory is broad in scope. It helps us make predictions about other phenomena. It is supported by a large body of evidence.

Is this clear?

Biology (the study of life) at various scales


An atom is a fundamental building block of all substances, living and non-living

http://archives.uvamagazine.org/site/c.esJNK1PIJrH/b.4101969/

Stable isotope analysis

Stephen Macko


Atoms joined with other atoms to form molecules

Many researchers have shown negative health impacts of trans fats


James Alexander Thomson

Cell- the smallest unit of life that can survive and reproduce on its own.


Organismal level


An individual that consist of on or more than one cell. For multicellular organisms scientists may focus on:•Tissue-an integrated group of cells with a common structure, function, or both•Organ-a body part consisting of two or more tissues•Organ system-a group of organs that work together to perform a vital function

Organisms are extremely diverse

Bacteria

Archea


http://upload.wikimedia.org/wikipedia/commons/f/f5/Grand_prismatic_spring.jpg

http://en.wikipedia.org/wiki/File:Rio_tinto_river_CarolStoker_NASA_Ames_Research_Center.jpg

Eukarya



Camille Parmesan

A group of individuals of the same species, interacting in a specified area.


All populations in a specified area.

James Estes, UCSC


A community interacting with its physical and chemical environment.

Gene Likens


Biosphere-encompasses all regions of the Earth’s crust, water, and atmosphere in which organisms live.

Lisa Curran


-Biology is exciting-Life is diverse, so is the scientific study of life (Biology)

Seven unifying themes of biology

New properties emerge at higher levels of biological hierarchies

Emergent properties- due to the arrangement and

interactions of parts, complexity increases


New properties emerge at higher levels of biological hierarchies

Emergent properties- due to the arrangement and

interactions of parts, complexity increases

This can be at odds with the reductionist approach to studying science


Organisms interact with their environments, exchanging energy and matter

Matter in-CO2 and nutrientsMatter out-O2 and decomposing biomass

Energy in-lightEnergy out-heat


What are these used for?


Structure and function are correlated


Structure and function are correlated

The idea that form and function are related would not be exemplified by which of the following examples?

a. Cells in the intestinal lining of vertebrates have many small projections that increase the surface area for absorption of nutrients.

b. Plants that live in dry areas have large roots for absorbing water.

c. Seeds that are dispersed by wind are very heavy.d. Fish that swim rapidly have bodies that are streamlined.e. Moles have large front paws for digging.


Cells are the organisms basic units of structure and function

• All organisms are composed of cells

• They are the lowest hierarchical level that is alive

• They share certain characteristics, but can be very diverse in form and function

Seven unifying themes of biologyFeedback mechanisms

regulate biological systems

Negative feedback-accumulation on an end product of a process slows that process

Positive feedback (less common)- end product speeds up production

Fig. 1-13

Negativefeedback

Excess Dblocks a step

D

D D

A

B

C

Enzyme 1

Enzyme 2

Enzyme 3

D

(a) Negative feedback

W

Enzyme 4

XPositivefeedback

Enzyme 5

Y

+

Enzyme 6

Excess Zstimulates astep

ZZ

Z

Z

(b) Positive feedback

Seven unifying themes of biologyFeedback mechanisms regulate biological

systemsWhich of the following examples would represent negative feedback?

a. As carbon dioxide levels rise in the blood of a mammal, the rate of breathing increases, leading to a decrease in blood levels of carbon dioxide.

b. As global temperatures rise, more ice melts, leading to greater planetary absorption of sunlight and additional temperature increase.

c. The speed of a racehorse decreases after running a mile.

d. The metabolic rate and energy consumption of grizzly bears decreases during hibernation.

e. Frog eggs hatch after five days of development at 28 degrees C but after 10 days of development at 23 degrees C.


The continuity of life is based on heritable info (from DNA)

•DNA controls the development and maintenance of all organisms

•It is similar across species

The core unifying theme of biologyIt explains how all life forms can be so

similar (ie. Possess the same genetic language and cell structure)

It also explains how life can be so diverse

“Nothing in biology makes sense except in the light of

evolution”

–T. Dobzhansky

The core unifying theme of biologyEvolution-change in the genetic composition of a

population over timeDarwin referred to evolution as decent with modification (a

more parsimonious explanation for the diversity of life)He proposed that the mechanism was natural selectionWhy?• He saw that individuals in populations varied and that

the variation was heritable• He saw that populations were producing more offspring

than could survive• He saw that species tended to be suited to their

environmentHe concluded that individuals with traits that are better

suited to the environment are more likely to survive and reproduce. This will lead to changes in the gene pool over time

The core unifying theme of biologyEvolution

Theories in SciencePeople who characterize evolution as “just a theory” show that they

a. know the difference between a hypothesis and a theory.b. do not understand that “theory” in science is a broad, overarching

concept that explains a variety of observations.c. think scientists use the term “theory” as a synonym for

“hypothesis.”d. understand how science accumulates information about the nature

of the natural world.e. understand how to develop scientific experiments.

You should understand:-What science is and how scientific knowledge is generated-What biology is and at what scales biologists study life-The diversity and unity of life-Evolution explains both the unity and diversity of life

Assignment:• Quiz on Monday

• Actively read chapter 2– Matter consists of chemical elements in pure

form and in combinations called compounds

– An element’s properties depend on the structure of its atoms

– The formation and function of molecules depend on chemical bonding between atoms

– Chemical reactions make and break chemical bonds

An introduction to biology with a focus on the unity and diversity of life.

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