Biology chapters 1-3

Biology

scientific study of life

Science

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

inquiry

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

what does biology begin with?

observation & exploration

observe

to watch the subject & record your observations

data

Recorded observations

scientific questions leads to…

testing

what makes a good question?

Answerable

Often ”why?”

Testable

Based on what is already known

Repeatable

When answered often lead to further questions…

hypothesis

a tentative answer to a well-framed scientific question

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a proposed explanation for a set of observations

hypothesis is usually

a rational accounting for a set of observations

results of an experiment

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

Scientists rely on

scientific literature to formulate questions

Scientists communicate

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

before publishing in a scientific journal they go through

peer review

peer review

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

fact

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

theory

a comprehensive and well-substantiated explanation

Law

a statement usually using math based on repeated experiments

Pseudoscience

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

How to detect pseudoscience

may be based solely or largely on anecdotal evidence

anecdotal evidence

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

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

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

Variables

factors that change in an experiment

controlled experiment

compares two or more groups that differ only in one variable

control group

acks or does not receive the specific factor being tested

experimental group

has or receives the specific factor being tested

independent variable

what is being manipulated by the researchers as a potential cause

dependent variable

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

placebo

Many medical drug trials include

Double-blind experiment

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

Structure & Function

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

Information Flow

necessary at all levels of biological organization

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

DNA

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

work

DNA (deoxyribonucleic acid)

Heredity (inheritable)

Stored in chromosomes

Contains genes

Programs cell

Blueprint for proteins

Work

Energy

Sun energy

major input, lost as heat energy

Sunlight

captured by photosynthetic organisms (producers)

consumed by consumers

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

Within all living cells

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

Energy transformations

can be disrupted often with dire consequences

Interactions

occur on the cellular to global level

At each level of interactions

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

emergent properties

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

evolution

Life is distinguished by its unity and its diversity

the process of change that has transformed life on Earth

lines of evidence of evolution

the similarities among fossil & living organisms

the common cellular processes

the universal chemical structure of DNA

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

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

Matter

anything that occupies space and has mass

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All organisms are composed of

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made up of elements

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cannot be broken down to other substances

Mass

a measure of the amount of material in an object

Element

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

all matter

is composed of chemical elements

Trace element

are required by an organism in only minute quantities

25 elements are essential for human life

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

Compounds

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

Atoms

Each element consists of one kind

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

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made of electrons, protons, and neutrons

Neutrons

no charge

electrons

negative charge

protons

positive charge

Isotopes

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

atom’s mass number

sum of the number of protons & neutrons in its nucleus

element’s atomic number

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

radioactive isotope

which the nucleus decays spontaneously

Radioactive decay

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

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

radioactive dating

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

fossil record

ordered sequence

chemical reactions

Only electrons are directly involved in it

The number of electrons in an atom determines

the chemical properties of that atom

Chemical reactions enable

atoms to transfer or share electrons.

chemical bonds

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

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

Ionic Bonds

formed between oppositely charged ions

ions

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

Atoms sometimes

strip electrons from their bonding partners

hydrogen bonds

polarity of water results in weak electrical attractions

chemical reactions

**changes in the chemical composition of matter**

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Cells constantly rearrange molecules

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can rearrange matter but cannot create or destroy matterwate

reactants

the starting materials

products

the end materials

water

Life on Earth began in water

Life evolved 3 billion years before spreading onto land

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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

How do water molecules stick together?

hydrogen bonding

Cohesion

the tendency of molecules of the same kind to stick together

much stronger for water than for most other liquids

surface tension

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

hydrogen bonds makes water unusually high

Ice floats

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

Floating ice

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

solution

liquid consisting of a homogeneous mixture of two or more substances

solvent

the dissolving agent

solute

the dissolved substance

Acid

a chemical compound that releases H + to a solution

Base

a compound that accepts H+ & removes them from solution

To describe the acidity of a solution chemists use this

PH scale

pH scale

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

Buffers

minimize changes in pH

cells

mostly water

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The rest, mainly of carbon-based molecules

Carbon

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

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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

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

functional groups

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

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Many biological molecules have two or more

Polymers

large macromolecules made by stringing together many smaller molecules called monomers

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

Hydrolysis

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

Macromolecule

a very large molecule important to biological processes

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4 categories