Biology ch 1

Theory

well-tested explanation that unifies a broad range of observations and hypotheses, and enables scientists to make accurate predictions about new situations

Fields of Biology

-Global ecology -biotechnology -building the tree of life -ecology and evolution of infectious diseases -genomics and molecular biology - performing biological investigations

1. Living organisms are made up of one or more cells- the smallest units considered fully alive

-cells can grow, respond to their surroundings, and reproduce -cells-complex/ highly organized - for example, a single branch of a tree contains millions of cells

4. Living organisms grow and develop

-during development, a single fertilized egg divides again and again -as these cells divide, they differentiate, which means they begin to look different from one another and to perform different functions

6. Living organisms respond to their environment

- a stimulus is a signal to which an organism responds - for example, some plants can produce unsavory chemicals to ward off caterpillars that feed on their leaves

7. Living organisms maintain a relatively stable internal environment , even when external conditions change dramatically.

- all living organisms expend energy to keep conditions inside their cells within certain limits - this condition process is homeostasis -ex: specialized cells help leaves regulate gases that enter and leave the plant

2. Living organisms are based on a universal genetic code

- all organisms store the complex information they need to live, grow, and reproduce in a genetic code written in a molecule called DNA -that info. is copied and passed from parent to offspring and is almost identical in every organism on earth

3. Living things obtain and use material and energy to grow, develop, and reproduce

- the combination of chemical reactions through which an organism builds up or breaks down materials is called metabolism -For example, leaves obtain energy from the sun and gases from the air. these materials then take part in various metabolic reactions within the leaves

8. over generations, groups of organisms evolve, or change over time

-evolutionary change links all forms of life to a common origin more than 3.5 bya -evidence of this shared history is found in all aspects of living and fossil organisms , from physical features to structures of proteins to sequences of info. in DNA -ex: signs of one of the first land plants, Cooksonia, are preserved in rock over 400 million years old

5. Living organisms reproduce, which means that they produce new similar organisms.

-most plants and animals engage in sexual reproduction, in which cells from two parents unite to form the first cell of a new organism -other organisms reproduce through asexual reproduction, in which a single organism produces offspring identical to itself -ex: beautiful blossoms are part of an apple tree's cycle of sexual reproduction

what is life?

-no single characteristic is enough to describe a living thing. ALL 8 MUST BE PRESENT! -some non-living things share one or more traits with organisms - Exception- Viruses- exists at the border between organisms and nonliving things

Characteristics of Living Organisms What does it mean to BE ALIVE?

1. made up of basic units called cells 2. are based on a universal genetic code 3. obtain and use materials and energy 4. grow and develop 5. reproduce 6. respond to their environment 7. maintain a stable internal environment 8. change over time

what are the central themes in Biology?

1.cellular basis of life 2. info and heredity 3. matter and energy 4. growth, development, and reproduction 5. homeostasis 6. evolution 7. structure and function 8. unity and diversity of life 9. interdependence in nature 10. science as a way of knowing

Law

a logical relationship between two or more things that is based on a variety of facts and proven hypothesis. it is often a mathematical statement of how two or more quantities relate to each other.

hypothesis

a proposed scientific explanation for observed phenomena; often takes the form of an "If...then" statement; scientists design experiments to determine whether the hypothesis is correct

belief

a statement that is not scientifically provable in the same way as facts, laws, hypotheses or theories

Controlled experiment

data are collected during the experiment; results of the experiment are recorded and analyzed; the scientist uses experimental results to determine whether the hypothesis was supported or refuted

controlled experiment

experiment in which only one variable is changed at a time

variable

factors in an experiment that can change

observation

of natural phenomena, often leads to questions

Biology

the study of life

independent variable

the variable that is deliberately changed (aka manipulated variable) 'If' statement

dependent variable

the variable that is observed and that changes in response to the manipulated variable (aka responding variable) 'Then' statement