Chapter 1 Section 3Studying Life

Biology

• Biology is defined as the study of living organisms and the processes they undergo.

Characteristics of Living things

A. Living things are made up of units called cells.B. Living things reproduce.C. Living things are based on a universal genetic code.D. Living things grow and develop.E. Living things obtain and use materials and energy.F. Living things respond to their environment.G. Living things maintain a stable internal environment.H. Taken as a group, living things change over time.

Living things are made of cells…

• A cell is a collection of living matter enclosed by a barrier that separates the cell from its surroundings.– Cells are the smallest unit of an organism that is

considered living.• Cells can grow.• Cells can respond to their surroundings.• Cells can reproduce

Living things are made of cells…

• Two types of living organisms..– Unicellular- single celled• Many microorganisms

– Multicellular- many-celled• The human body alone has 85 different cell types.

Reproduction

• Reproduction is the process in which organisms produce new organisms.– Two Types:

A. Sexual Reproduction: cells from two different parents unite to produce the first cell of the new organism.

B. Asexual Reproduction: the new organism has a single parentA. BuddingB. FissionC. Fragmentation

Based on a Genetic Code…

• Organisms usually resemble their parents.– Asexual reproduction produces offspring that are

the same as their parents.– Sexual reproduction produces offspring that differ

from their parents in some ways.• The code is know as deoxyribonucleic acid.

DNA.

Growth and Development…

Need for Materials and Energy…

• Organisms use energy and a constant supply of materials to grow.– Metabolism is the combination of chemical

reactions through which an organism builds up or breaks down materials as it carries out its life processes

• All organisms take in selected materials from their surrounding or environment.

Responses to the Enviroment…

• Organisms detect and respond to stimuli from their environment.– A Stimulus is a signal to which an organism

responds.• Seeds respond to warm soil and water by germinating.• Roots respond to gravity by growing downward.• Leaves grow toward light.• You feel hungry when you blood sugar is getting low.

Maintaining Internal Balance

• Most organisms must keep internal conditions such as temperature and water content fairly stable to survive.– Homeostasis is the process by which organisms

maintain a relatively stable internal conditions.• Sweating • Shivering• Feeling thirsty

Evolution

• Most organisms experience many changes during their lives, however traits they inherited from their parents usually do not change.– Organisms change with time to survive in a world

that is always changing.

Branches of Biology• Zoology- Study of animals• Botany- Study of plants• Paleontology- Study of ancient life• Ecology - Study of the relationships between plants, animals, and

their environment • Ethology - the study of animal behavior • Entomology - the scientific study of insects• Ichthyology - the study of fishes• Herpetology - the study of reptiles and amphibians• Ornithology - the study of birds• Mammalogy - the study of mammals• Primatology - the science that deals with primates