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Biology Exploring Life

All forms of life share common properties

Life is defined by what living things do. 7 major processes/properties associated with living things Have order (all living things are either single cells or

made of many cells)- atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms

Reproduce: make more of their own (cell division/sexual reproduction)

Grow and develop: increase in size, go through a series of changes (development) controlled by DNA

Process energy: use energy to carry out all life functions and to maintain homeostasis (internal balance)

Respond to the environment: stimulus/response (migration, movement toward light, etc.)

Regulation: have processes that regulate a constant internal environment (homeostasis) (shivering,

Hierarchy of Organization

At each level of organization new properties arise that were not present at the preceding level. (Emergent Properties)

Living organization begins at the cellular level. All living things are made of cells. Cells are made of atoms, molecules, and organelles-but these are not considered living. DNA is an important molecule, but it is not a living thing Organelles are tiny “organs” that perform a specific function

for a cell, but alone they are not considered living

A group of similar cells that perform a specific function are tissues-tissues are considered living

A group of tissues form an organ (heart)

A group of organs form an organ system (circulatory system)

A group of organ systems form an organism (an individual living thing)

A group of organisms of the same species form a population

A group of populations form a community (plants and animals, fungi, bacteria)

A group of communities form and ecosystem

Groups of ecosystems form the biosphere (all of the ecosystems on earth that support life.)

Cells are the structural and functional units of life

Cells are the level of organization at which the properties of life emerge

All organisms are composed of cells. They occur singly or as the subunits of multicellular organisms.

Two main characteristics of cells 1. All cells are enclosed in a membrane that regulates

what enters and leaves the cell 2. All cells use DNA as genetic information

2 types of cells: 1. Prokaryotic: DNA is not enclosed in a membrane

bound nucleus. No membrane bound organelles. Smaller in size Have existed on Earth for longer (evolved around the first

1.5 billion years of life on Earth 2. Eukaryotic: DNA contained within a membrane

bound nucleus. Contains membrane bound organelles. Larger in size Evolved about 2.1 billion years ago

The properties of life emerge from the ordered arrangement and interaction of the structure of cells.

A system is the combination of the parts forming a more complex organization.

Because of the complexity of biological systems, biologists use an approach called systems biology which uses models to study the dynamic behavior within a system. Systems biology is based on the study of the individual parts of the system to explain the whole system.

Cells also help explain the correlation between structure and function. A cells structure gives us clues as to it’s function (nerve cells)

All activity from movement to metabolism takes place at the cellular level.

Organisms Interact with their Environment

This interaction includes all living and non-living parts.

There are two major processes that are involved in this interaction 1. Recycling of chemical nutrients

producersconsumersconsumersdecomposers producers

Nurtients are recycled through the ecosystem

2. The flow of energy SunlightProducerschemical

heatConsumerheatDecomposterheat There must be a constant source of sunlight and

heat is given off in each step in the flow of energy through the system. This means that each step has less available energy than the previous step.

The Unity of Life is Base on DNA and a Common

Genetic Code

DNA is the chemical substance of genes. Genes are the units of inheritance and all cells have DNA

The molecular structure of DNA controls the transmittance of information from parents to offspring and controls the activities of the cell.

The diversity of life arises from the differences in the DNA sequence of nucleotides

DNA stand for Deoxyribonucleic Acid

DNA is composed of long chains of nucleotides

Nucleotides A ribose sugar A phosphate group A nitrogen base

The Diversity of Life is Arranged into Three

Domains

Life is not only organized within the biosphere from molecules to the biosphere, life is organized according to the diversity of living things.

Living things are grouped according to similarities. This grouping process (taxonomy) names and classifies species into a hierarchy of broader and broader groups: genus, family, order, class, and phylum to kingdom

Historically, biologists grouped all living things into 5 kingdoms

Using evolutionary relationships we now group all living things into one of three domains Domain Bacteria (Prokaryotes, very diverse group) Domain Archaea (Prokaryotes, live in very harsh

environments-salty lakes, boiling hot springs) Domain Eukarya (Eukaryotes, range from single cell

protists to multicellular organisms)

Evolution explains the Unity and Diversity of Life

Fossils document the history of the changing Earth Life has existed on Earth for billions of years The Earth has been inhabited by an evolving cast of

life forms

Evolution accounts for life’s: Kinship(Similarities) and Diversity Differences

Charles Darwin

Published On the Origin of Species by Means of Natural Selection in 1859 Provided evidence to support the idea of evolution

and that species living today are descendants of ancestral species (descent with modification)

Natural Selection is the mechanism for evolution

Darwin made two observations: 1. Individuals in a population vary in their traits,

many of which are passed from parent to offspring 2. A population can produce more offspring than the

environment can support

From these observations, Darwin inferred: 1. Individuals with heritable traits best suited to the

environment are more likely to survive and reproduce than less well-suited individuals

2. This unequal reproductive success over many generations will increase the proportion of individuals in the population with the advantageous traits

3. This will result in an evolutionary adaptation. The accumulation of favorable traits in a population over time.

The Process of Science

Science: derived from the Latin verb “to know”

Scientists use inquiry: search for information and explanation 1. Discovery Science 2. Hypothesis-based Science

Discovery Science Describes nature through observation and analysis

of data Data = recorded observations

(quantitative/qualitative) Inductive reasoning: generalizations derived from

specific observations

Hypothesis-Based Science Uses deductive reasoning: propose an explanation

for a set of observations. Logic flows from general to specific.

Hypothesis: predictions that can be tested by observing or experimenting.

AP Biology will use: “If…., then ….. because” when writing our hypotheses.

A hypothesis must be testable and falsifiable

Experimental Design

Hypothesis

Use control (the group in the experiment you will compare your results to) and experimental (the group that contains the factor you will be testing or observing) Controlled Experiment

Design: Independent variable (IV) A variable that is changed intentionally to observe

its affect on the dependent variable Dependent variable (DV) What you measure in the experiment, what is

affected during the experiment Control Constants # of trials

Example: You are interested in how stress affects heart rate in humans. Your independent variable would be the stress and the dependent variable would be the heart rate. You manipulate stress levels in your subjects and measure how those stress levels change heart rate.

Hypothesis

Explanation to a specific question

Tested by experimentation or continued observation

Can be disproven (falsified) but cannot be proven true

Theory

Summarizes a group of hypotheses supported by repeated testing

Broader in scope

New hypotheses can be generated from it

Supported by massive body of evidence

Law

Statement of Fact

Explains things but doesn’t describe them

Generally accepted to be true and universal

Basis for scientific method

Science is a social activity with most scientists working in teams

Scientists share information

Science seeks natural causes for natural phenomena Limited to the study of structures and processes that wen

can directly observe and measure Hypotheses about supernatural forces or explanations are

outside the bounds of science because they generate untestable hypotheses

Biology and Everyday Life

Biology, technology, and society are connected.

Issues facing society are related to biology and most involve expanding technology

The goals of science and technology differ The goal of science is to understand natural

phenomena The goal of technology is to apply scientific

knowledge for a specific use

Technology advances stem from scientific research Scientific research benefits from new technology

Evolution is a core theme in biology Evolution is useful in medicine, agriculture,

forensics, and conservation

Human caused environmental changes are powerful selective forces that affect the evolution of many species Antibiotic resistant bacteria Pesticide resistant pests Endangered species and extiction