Chapter 2 Section 2 What is a living system?

2.2 What is a Living System? As a living system, your body is organized to use matter and energy to move, grow, and survive.

2.2 What is a Living System? Living systems are made of many different molecules. A molecule is a basic unit of matter. Your body contains molecules that store energy, control life functions, and even hold all of the genetic information.

2.2 What is a Living System? Living systems—like you—contain many levels of organization: –A cell is the basic unit of a living system. –A group of specialized cells that performs a particular function are grouped together as a tissue. –An organ is a group of tissues that works together to carry out a set of functions. –A group of organs that works together to perform a set of functions is called an organ system.

Organization of living systems

Variables and Living systems Homeostasis: process of maintaining a life- supporting internal environment Different Variables affect an organism’s ability to live: Temperature Food Water Level of oxygen Homeostasis helps organisms maintain those variables at a level that keeps the organism living. –Ex: if you are in a place that is too hot or too cold, your body will adjust it’s internal temperatures to keep you alive under the circumstances

4.3 Light and living things The microscope magnifies objects so you can see their very small features. Light is very important to all living things.

4.3 Light Light is a form of energy. Light given off from objects like a light bulb or the Sun travels in straight lines.

4.3 Reflection Reflection occurs when light bounces off of a surface.

4.3 Law of reflection The incident ray is the light ray that strikes the surface of the mirror. The reflected ray is the light ray that bounces off the surface of the mirror.

4.3 Reflection Surfaces, such as polished wood, are in between smooth mirrors and rough concrete and create two types of reflection.

4.3 Refraction Refraction is the bending of light as it crosses a boundary between two different transparent materials.

4.3 Refraction Do you think this illusion would still happen if there were no water in the glass? Try it and see.

4.3 Lenses A lens is an object that is designed to refract light in a specific way. Many devices you use contain lenses.

4.3 Lenses There are two basic kinds of lenses: –convex –concave

4.3 Lenses Light rays that enter a convex lens parallel to its axis refract and meet at a point called the focal point.

4.3 Lenses Light rays that enter a concave lens parallel to its axis refract and spread out

4.3 Microscopes Most microscopes use at least two lenses. The lens closest to the object to be viewed is called the objective. The lens you look through is called the eyepiece.

Microscopes - Leeuwenhoek Antony van Leeuwenhoek was known as the “Father of Microscopy” He made some of the most important discoveries in the history of biology His researches, which were widely circulated, opened up an entire world of microscopic life to the awareness of scientists

Microscopes - Janssen Around 1590, two Dutch spectacle makers, Zaccharias Janssen and his father Hans started experimenting with these lenses. They put several lenses in a tube and made a very important discovery. The object near the end of the tube appeared to be greatly enlarged, much larger than any simple magnifying glass could achieve by itself! They had just invented the compound microscope (which is a microscope that uses two or more lenses).

Microscopes - Hooke Robert Hooke was the first to study and record cells by using a microscope. Hooke had discovered plant cells -- more precisely, what Hooke saw were the cell walls in cork tissue. In fact, it was Hooke who coined the term "cells": the boxlike cells of cork reminded him of the cells of a monastery. Hooke also reported seeing similar structures in wood and in other plants

A.Eye Piece : Contains the ocular lens B.Nose Piece Holds the high and Low power objective lenses; can be rotated to change magnification C. Objective Lenses Magnification ranges from 10 x to 40x D. Stage Clips: supports the slide in place E. Stage: supports the slide being viewed F. Light Source: Projects light upwards through the diaphragm, the slid/specimen and the lens G. Base: supports the microscope H. Diaphragm: Regulates the amount of light on the specimen I.Fine Adjustment knob Moves the stage slightly to sharpen the image J. Course Adjustment knob Moves the stage up and down for focusing K. Arm: used to support the microscope when carried