Biology chapters 1-3

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Biology

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1

Biology

scientific study of life

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Science

is an approach to understanding the natural world that is based on inquiry

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inquiry

a search for information, evidence, explanations, and answers to specific questions

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what does biology begin with?

observation & exploration

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observe

to watch the subject & record your observations

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data

Recorded observations

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scientific questions leads to…

testing

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what makes a good question?

Answerable

Often ”why?”

Testable

Based on what is already known

Repeatable

When answered often lead to further questions…

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hypothesis

a tentative answer to a well-framed scientific question

a proposed explanation for a set of observations

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hypothesis is usually

a rational accounting for a set of observations

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results of an experiment

will either support or not support the hypothesis. There is no “proving” or being “correct” in science

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Scientists rely on

scientific literature to formulate questions

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Scientists communicate

findings with each other with seminars, meetings, and scientific publications

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before publishing in a scientific journal they go through

peer review

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peer review

research is evaluated by qualified, impartial, & anonymous experts who were not involved in the study

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fact

is a piece of information considered to be objectively true based on all current evidence

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theory

a comprehensive and well-substantiated explanation

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Law

a statement usually using math based on repeated experiments

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Pseudoscience

any field of study that is falsely presented as having a scientific basis

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How to detect pseudoscience

may be based solely or largely on anecdotal evidence

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anecdotal evidence

an assertion based on a single or a few examples that do not support a generalized conclusion

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features of science

Adheres to an established and well-recognized scientific method

Repeatable results

Testable claims that can be disproven

Open to outside review

Multiple lines of evidence

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features of Pseudoscience

Does not adhere to generally accepted processes of science

Results that cannot be duplicated by others;results that rely on a single person or are solely opinion

Unprovable or untestable claims; reliance on assumptions or belief that are not testable

Rejection of external review or refusal to accept contradictory evidence

Overreliance on a small amount of data; underlying causes are not investigated

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Variables

factors that change in an experiment

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controlled experiment

compares two or more groups that differ only in one variable

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control group

acks or does not receive the specific factor being tested

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experimental group

has or receives the specific factor being tested

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independent variable

what is being manipulated by the researchers as a potential cause

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dependent variable

the response, output, or effect under investigation that is used to judge the outcome of the experiment

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placebo

Many medical drug trials include

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Double-blind experiment

in which neither the participant nor the experimenter knows which group is the control group

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Structure & Function

At different levels within biological systems: Within molecules, cells, tissues, and organs

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Information Flow

necessary at all levels of biological organization

Life’s Processes involve the expression and transmission of genetic information

DNA

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Movement, growth, reproduction, and cellular activities of life are

work

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DNA (deoxyribonucleic acid)

Heredity (inheritable)

Stored in chromosomes

Contains genes

Programs cell

Blueprint for proteins

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Work

Energy

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Sun energy

major input, lost as heat energy

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Sunlight

captured by photosynthetic organisms (producers)

consumed by consumers

This energy is converted into chemical energy, & stored as chemical bonds within sugars

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Within all living cells

network of chemical reactions (metabolism) continually converting energy from one form to another

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Energy transformations

can be disrupted often with dire consequences

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Interactions

occur on the cellular to global level

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At each level of interactions

complexity increases & novel properties emerge that are absent from the preceding one

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emergent properties

are due to the specific arrangement & interactions of many parts into an increasingly complex system

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evolution

Life is distinguished by its unity and its diversity

the process of change that has transformed life on Earth

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lines of evidence of evolution

the similarities among fossil & living organisms

the common cellular processes

the universal chemical structure of DNA

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theory of evolution by natural selection

Charles Darwin published: On the Origin of Species by Means of Natural Selection:

1. Species living today arose from a succession of ancestors that were different from them in a process Darwin called "descent with modification."

2. The process of natural selection is the driving force of evolution

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Evolution by Natural Selection

Individuals with traits best suited to the local environment are more likely to survive and leave the greatest number of healthy offspring. This unequal reproductive success is because the environment "selects" only certain heritable traits from those already existing

occurs on a POPULATION level

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Matter

anything that occupies space and has mass

All organisms are composed of

made up of elements

cannot be broken down to other substances

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Mass

a measure of the amount of material in an object

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Element

a substance that cannot be broken down into other substances by chemical reactions

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all matter

is composed of chemical elements

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Trace element

are required by an organism in only minute quantities

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25 elements are essential for human life

4 elements (Oxygen, Carbon, Hydrogen and Nitrogen) make up 96% of most living organismsCompounds

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Compounds

made up of two or more different elements in a fixed ratio

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Atoms

Each element consists of one kind

smallest unit of matter that still retains the properties of an element

made of electrons, protons, and neutrons

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Neutrons

no charge

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electrons

negative charge

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protons

positive charge

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Isotopes

have the same number of protons and behave identically in chemical reactions, but they have different numbers of neutrons

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atom’s mass number

sum of the number of protons & neutrons in its nucleus

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element’s atomic number

All atoms of a particular element have the same unique number of protons

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radioactive isotope

which the nucleus decays spontaneously

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Radioactive decay

can be used to obtain important data about the evolutionary history of life on Earth

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fossils

reliable chronological records of life

age can be estimated by measuring the ratio of the two isotopes to learn how many half-life reductions have occurred since it died

With radioactive dating scientists can estimate the ages of it & place them

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radioactive dating

scientists can estimate the ages of fossils & place them in fossil records

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fossil record

ordered sequence

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chemical reactions

Only electrons are directly involved in it

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The number of electrons in an atom determines

the chemical properties of that atom

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Chemical reactions enable

atoms to transfer or share electrons.

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chemical bonds

enabling atoms to transfer or share electrons usually result in atoms staying close together

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Covalent bonds

forms when two atoms share one or more pairs of electrons

are the strongest of the various bonds

hold atoms together in a molecule

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Ionic Bonds

formed between oppositely charged ions

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ions

atoms or molecules that are electrically charged as a result of gaining or losing electrons

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Atoms sometimes

strip electrons from their bonding partners

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hydrogen bonds

polarity of water results in weak electrical attractions

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chemical reactions

changes in the chemical composition of matter

Cells constantly rearrange molecules

can rearrange matter but cannot create or destroy matterwate

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reactants

the starting materials

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products

the end materials

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water

Life on Earth began in water

Life evolved 3 billion years before spreading onto land

The abundance of water is a major reason that Earth is habitable

The polarity of water molecules and the hydrogen bonding that results explain most of water’s life-supporting properties

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How do water molecules stick together?

hydrogen bonding

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Cohesion

the tendency of molecules of the same kind to stick together

much stronger for water than for most other liquids

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surface tension

a measure of how difficult it is to stretch or break the surface of a liquid.

hydrogen bonds makes water unusually high

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Ice floats

it is less dense than the liquid water in which it is floating

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Floating ice

acts as an insulating “blanket” over liquid water, allowing life to persist under the frozen surface

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solution

liquid consisting of a homogeneous mixture of two or more substances

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solvent

the dissolving agent

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solute

the dissolved substance

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Acid

a chemical compound that releases H + to a solution

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Base

a compound that accepts H+ & removes them from solution

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To describe the acidity of a solution chemists use this

PH scale

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pH scale

a measure of the hydrogen ion H + concentration in a solution

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Buffers

minimize changes in pH

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cells

mostly water

The rest, mainly of carbon-based molecules

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Carbon

forms large, complex, and diverse molecules necessary for life’s functions

can share electrons with other atoms in four covalent bonds

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Organic compounds

carbon-based molecules

can also bond with other elements, most commonly hydrogen, oxygen, and nitrogen

depend on its carbon skeleton and the atoms attached to the skeleton

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functional groups

the groups of atoms directly involved in chemical reactions as part of organic compound

Many biological molecules have two or more

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Polymers

large macromolecules made by stringing together many smaller molecules called monomers

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dehydration reaction

links two monomers together &

removes a molecule of water

link nucleotide monomers into long chains called polynucleotides form covalent bonds between the sugar of one & the phosphate of the next

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Hydrolysis

breakdown of polymers occurs by adding water to them, a process that is essentially the reverse of a dehydration reaction

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Macromolecule

a very large molecule important to biological processes

4 categories

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