ملخص Exploring Life في العلوم باللغة الإنجليزية للصف السادس - الفصل الثاني (2)

Exploring life - LESSON (1)

A. All living things have seven characteristics in common. 1. Made of cells 2. Organization 3. Growth and development 4. Reproduction 5. Response to stimuli 6. Maintaining internal conditions 7. Using energy

B. The first characteristic that living things have in common is what they are made of. C. Cells are called the “building blocks of life” because all living things are made up of cells. D. Principles of cell theory

Types of microscopes: 1- Light microscopes:

• It uses light and lenses to enlarge an image of an object. • It can enlarge images up to 1,500 times its original size. • It is used in school.

2- Electron microscopes: • It uses a magnetic field to focus a beam of electrons through an object or onto

an object’s surface. • It can magnify an image up to 100,000 times or more. • There are two main types of electron microscope:

A. Transmission electron microscopes (TEMs) • TEMs are usually used to study extremely small things such as cell structures. In a TEM, electrons pass through the object and a computer produces an image of the object

B. Scanning electron microscopes (SEMs) • SEMs are usually used to study an object’s surface. (outside) In an SEM, electrons bounce off the object and a computer produces a threedimensional image of the object

How many cells do living things have? ➢ Living things that are made of only one cell are called unicellular organisms. ➢ Living things that are made of two or more cells are called multicellular organisms.

There are two main types of cells: 1. Prokaryotic cells 2. Eukaryotic cells

Prokaryotic cells

unicellular organisms Contain genetic materials - how information is transmitted from one

generation to the next Not surrounded by a lining.

Small Have fewer parts to their cells

Example: Bacteria

Some prokaryotes live in small groups called colonies. Some live in extreme climates

Eukaryotic cells

multicellular organisms Contain genetic materials - how information is transmitted from one

generation to the next surrounded by a lining.

large Have many parts to their cells (called

organelles) Example: plants, animals, and

humans، Classifications