The Nature of Life

Francesco Redi showed that cells are never formed by non-living things Francesco Redi showed that cells are never formed by non-living things. Cells come only from other cells. He proved that live cells come from other living cells. http://www.kent.k12.wa.us/staff/TimLynch/sci_class/chap01/redi.html

All living things are made of cells All living things are made of cells. Some living things contain only a single cell. Single-celled or unicellular organisms include microscopic bacteria. (uni means one so unicellular means single-celled). This one cell can perform all the functions necessary for their life.

Most of the living things you are familiar with contain many cells, or multicellular.

Responding to the Environment Scientists call each of the signals to which an organism reacts a stimulus. A stimulus is any change in the environment, or surroundings of an organism that produces a response by that organism. A response is some action, movement, or change in behavior of the organism.

Living Things Reproduce There are two different types of reproduction: sexual reproduction and asexual reproduction.

Sexual reproduction usually requires two parents and the offspring looks similar to its parents. Most multicellular forms of plants and animals reproduce sexually.

Some living things reproduce from only one parent and the offspring looks identical to its parent. This is asexual reproduction. When an organism divides into two parts, it is reproducing asexually. Bacteria reproduce this way. Yeast forms growths called buds, which break off and then form new yeast plants. Geraniums and African violets grow new plants from part of a stem, root, or leaf of the parent plant.

Types of Reproduction https://www.youtube.com/watch?v=oHTqpYObFZ8

The Transfer of the Sun’s Energy The primary source of energy for most living things is the sun. Plants use the sun’s light energy to make food. Some animals feed on plants and in that way obtain the energy stored in the plants. Other animals then eat the plant eaters. In this way, the energy from the sun is passed on from one living thing to another.

Photosynthesis

Well most of it anyway…… Where does the energy come from that sustains all life? The Sun!! Well most of it anyway……

Overview

Carbon dioxide and water are taken in by plants. Plants absorb light energy and convert it to a usable form.

Formula for Photosynthesis 6 CO2 + 6 H2O→ C6H12O6 + 6 O2 Carbon dioxide + Water + Light energy → Glucose + Oxygen

Photosynthesis takes place within the chloroplasts of plant cells. Image source: http://www.daviddarling.info/encyclopedia/C/chloroplasts.html