1. Science of Biology

2. Biology The scientific study of life
Nature is not neatly packaged into the individual life sciences.
Organisms and their environment are natural systems to which the basic concepts of chemistry and physics apply.
Biology is a multidisciplinary science, drawing on the insights from other sciences.

3. What is Life?
Life resists a simple, one-sentence definition, yet we can recognize life by what living things do.
All organisms share a common set of features or properties

4. Properties of Life Form high degree of ordered structures
Form high degree of ordered structures
Regulate internal conditions

5. Properties of Life
Harvest and use energy
Reproduce and evolve

6. Properties of Life
Grow and develop
Respond to environmental stimuli

7. Organizational Hierarchy
Biosphere
Ecosystem
Florida coast
Community
All organisms on
the Florida coast
Population
Group of brown
pelicans
Organism
Brown pelican
Organ system
Nervous system
Organ
Brain
Tissue
Nervous tissue
Cell
Nerve cell
Organelle
Nucleus
Molecule
DNA
Atom
Spinal cord
Nerve
Life can be organized into a hierarchy of structural levels.
At each successive level additional emergent properties appear.
Fig. 2.1

8. The hierarchy of Life Organ systems Organs Tissues Cells Organelles
Organ systems
Organs
Tissues
Cells
Organelles
Molecules
Biologists investigate the full spectrum of life, from the biosphere to the biochemical reactions within a cell.

9. Emergent Properties
Life’s basic characteristic is a high degree of order
Biological organization is based on a hierarchy of structural levels, each building on the levels below
Novel properties emerge at each step upward
Emergent properties result from interactions between components
Emergent properties reflect importance of structural arrangement and organization

10. Reductionism
The complex organization of life presents a dilemma to scientists seeking to understand biological processes.
We cannot fully explain a higher level of organization by breaking it down into parts.
At the same time, it is futile to try to analyze something a complex as an organism or cell without taking it apart.
Reductionism - Reducing complex systems to simpler components, is a powerful strategy in biology.
Reductionism is balanced by the longer-range objective of understanding emergent properties.

11. Unity and Diversity Biology can be viewed as having two dimensions:
A “vertical” dimension covering the size scale from atoms to the biosphere
A “horizontal” dimension that stretches across the diversity of life.
The latter includes not only present day organisms but those throughout life’s history.

12. Diversity - Hallmark Of Life
At present, biologists have identified and named about 1.5 million species.
This includes over 280,000 plants, almost 50,000 vertebrates, and over 750,000 insects.
Thousands of newly identified species are added each year.
Estimates of the total diversity of life range from about 5 million to over 30 million species.

13. Unity
Underlying the diversity of life is a striking unity, especially at the lower levels of organization.
The universal genetic language of DNA unites prokaryotes, like bacteria, with eukaryotes, like humans.
Among eukaryotes, unity is evident in many details of cell structure.
Fig. 1.12

14. Unity and Diversity
Evolution is the key to understanding biological diversity
The evolutionary connections among all organisms explain the unity and diversity of life
Descent with modification accounts for both the unity and diversity of life.
In many cases, features shared by two species are due to their descent from a common ancestor.
Differences are due to modifications by natural selection modifying the ancestral equipment in different environments.
Evolution is the core theme of biology - a unifying thread that ties biology together.

15. Evolution Can explain the unity and diversity of life
Can explain the unity and diversity of life
Charles Darwin synthesized the theory of evolution by natural selection, his book on evolution presented two important concepts.
Species evolved from ancestors, and there was modification in the process or, as Darwin stated, “descent with modification.”
Natural selection occurs as heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others.

16. Darwin’s Observations
Individual Variation - Individuals in a population of any species vary in many heritable traits
Differential reproductive success –
Any population can potentially produce far more offspring than the environment can support
This creates a struggle for existence among variant members of a population.
Darwin inferred that those individuals with traits best suited to the local environment will generally leave more surviving, fertile offspring

17. Natural Selection Natural selection is an editing mechanism
Occurs when populations or organisms, having inherited variations, are exposed to environmental factors that favor the reproductive success of some individuals over others

18. Struggle for Existence
Struggle for existence: A population produces many more offspring than can survive long enough to reproduce. This idea was based on Thomas Malthus’s Essay on the Principle of Population – populations tend to increase faster than their food supply.
This leads to competition and is of great consequence in differential reproductive success

19. Natural Selection
Natural selection, by its cumulative effects over vast spans of time, can produce new species from ancestral species.
For example, a population may be fragmented into several isolated populations in different environments.
What began as one species could gradually diversify into many species.
Each isolated population would adapt over many generations to different environmental problems

20. Finches Of The Galapagos Islands
Diversified after an initial colonization from the mainland to exploit different food sources on different islands.

21. Descent With Modification
Descent with modification accounts for both the unity and diversity of life.
In many cases, features shared by two species are due to their descent from a common ancestor.
Differences are due to modifications by natural selection modifying the ancestral equipment in different environments.
Evolution is the core theme of biology - a unifying thread that ties biology together.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

22. Adaptation
The product of natural selection is adaptation, the collection of favorable modifications in a population over time.
All organisms have adaptations that have evolved by means of natural selection

23. The Process Of Science
Scientists use two main approaches to learn about nature
Discovery Science - Scientists describe some aspect of the world and use inductive reasoning to draw general conclusions
Hypothesis-Based Science - Scientists attempt to explain observations by testing hypotheses

24. The Process Of Science There are no absolute truths in science
All that we understand about nature comes from our ability to observe the world around us.
Scientists do not “believe” in something
Instead scientists have levels of confidence in explanations for natural phenomena.

25. Scientific Theory
Broad in scope, generates hypotheses, supported by massive body of evidence. Theories constantly challenged through testing of the specific, falsifiable hypotheses they generate.
Einstein’s Theory of General Relativity
Darwin’s Theory of Evolution
Lemaître’s Big Bang Theory of the Universe

26. Hypothesis-based Science
Hypothesis-based science involves:
Observations, questions, hypotheses as tentative answers to questions
Deductions leading to predictions, and then tests of predictions to see if a hypothesis is falsifiable

27. What is a hypothesis?
A hypothesis is a tentative or educated guess at an answer to a problem or question that is being asked.
A good hypothesis makes predictions that can be tested.
Part of the process of hypothesis-based science uses deductive reasoning, which flows from a general premise to a specific premise.
The important aspect of this process is that the deduction can be tested.

28. Hypothesis-based Science
A Case Study from Every day Life
Deductive reasoning is used in testing hypotheses as follows
Observations
Question
Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Replacing bulb
Test prediction
Test falsifies hypothesis
Test does not falsify hypothesis

29. Hypothesis-based Science
Two important qualities of the hypothesis-based science illustrated in the flashlight example
A hypothesis must be testable.
A hypothesis must be falsifiable
If a hypothesis is correct, and we test it, then we can expect a particular outcome

30. Key Steps in the Scientific Method
Make observations, may come from others or results of earlier tests
Ask questions about aspects of the observations: How? Why? When?
Generate hypotheses; explanations of the phenomena, phrased in such a way as to be testable.
Derive predictions; logical, testable outcomes of the hypotheses
Developed by the use of deductive reasoning
Predictions take the form of if (statement of hypothesis) is true, then (predictions).
Test the predictions; performed to determine if the predictions are supported (fail to falsify) or falsified
A hypothesis becomes credible when repeated attempts to disprove it fail

31. In Science and Medicine, We use the Metric System!

32. Base Units Unit of length: meter Unit of mass: kilogram
Unit of volume: liter
Unit of temperture: degree Celsius

33. SI Base Units of Measurement
Mass = gram = g
1 gram ≈ 1/28 ounce
Length = meter = m
1 meter ≈ yard
Volume = liter = l
defined as 1000 cubic centimeters
1 liter ≈ quart
Temperature = degrees Celsius; oC

34. Prefixes The metric system uses prefixes to represent units
smaller and larger than the fundamental unit by factors of 10.
For example, a centimeter is 1/100 of a meter, and a kilometer is 1000 times a meter
For very large numbers, we use the powers-of-ten notation, e.g. 102 = 100, 106 = 1,000,000, 10-2 = 0.01

35. Prefixes
One of the clever ideas behind the system was to use only multiples of ten.

36. Converting Between Metric Units
To convert from a LARGER unit of measure to a SMALLER unit of measure, MULTIPLY by the “order-of-magnitude difference” between the units.
Example: 1.2 mg = ______ g
1 mg = 1000 g
1.2 mg = 1.2 x 1000 g = 1200 g
Remember to check if your answer is logical.
It should take a GREATER NUMBER of SMALL UNITS to equate to a LESSER NUMBER of LARGE UNITS.
A microgram is smaller than a milligram (by a factor of 1000), so a given number of milligrams should be equal to many more micrograms (1000 times as many).

37. Converting Between Metric Units
To convert from a SMALLER unit of measure to a LARGER unit of measure, DIVIDE by the “order-of-magnitude difference” between the units.
Example: 250 ml = ______ l
1 l = 1000 ml
250 ml = 250 ÷ 1000 l = 0.25 l
Is your answer is logical?
It should take a LESSER NUMBER of LARGE UNITS to equate to a GREATER NUMBER of SMALL UNITS.
A liter is larger than a milliliter (by a factor of 1000), so a given number of milliliters should be equal to fewer liters (1/1000 as many).

38. Thinking in Metric Units of Length
1 kilometer = ~0.62 or ~5/8 mi
1 meter = 1.09 yard = 39.4 in
1 centimeter = ~4/10 inch
1 angstrom = 1/10 nm or 10-10m
1 mile = ~1.6 km
1 yard = ~0.91 m
1 foot ~30.5 cm
1 inch = ~2.54 cm

39. Thinking in Metric Units of Volume
1 liter = ~1.06 quart
1 milliliter = 1 cubic cm (1cc) ~"a thimble full"
Examples
1 teaspoon ≈ 5ml
12 oz. soda ≈ 360 ml
2-liter bottle of soda
1 gallon = ~3.8 l
1 quart = ~0.95 l
1 pint = ~0.47 l
1 cup = ~240 ml
1 fluid oz. ~30 ml
2 liters~1/2 gal.

40. Thinking in Metric Units of Mass
1 kilogram = 2.2 pounds
1 gram = ~"a thimble full" of water
Examples
70 kg human = 154 lbs.
1 ml of water weighs ~1 g
1 pound = 454 g
1 ounce = ~28 g

41. Estimate The length of: The volume of: The mass of: your bare foot
your driveway
The volume of:
a coffee cup
a bottle of shampoo
The mass of:
a steak
a dog

42. Celsius: The Metric Temperature Scale
Also called the centigrade scale.
Definitions
0 Celsius = 32 Fahrenheit = water freezes
100 Celsius = 212 Fahrenheit = water boils
Therefore, 1C = 1.8F
Conversions
 Celsius = 5/9 x ( Fahrenheit - 32)
 Fahrenheit = (9/5 x  Celsius) + 32
100C
212F
0C
32F

43. Thinking in Celsius -10 Celsius = frigid (14 F)
0 Celsius = cold (32 F)
10 Celsius = cool (50 F)
20 Celsius = comfortably warm (68 F)
30 Celsius = hot (86 F)
40 Celsius = very hot (104 F)
What would you wear outside in tempsf:
10C, 0C, 10C, 20C, 30C?