Results

These three short online lessons discuss asteroids, comets and meteors.

Plant cells have a cell wall in addition to a cell membrane, whereas animal cells have only a cell membrane. Plants use cell walls to provide structure to the plant. Plant cells contain organelles called chloroplasts, while animal cells do not. Chloroplasts allow plants to make the food they need to live using photosynthesis.

The Earth behaves like a giant bar magnet and as such there is a magnetic field present around it. The Earth’s magnetic field is thought to be caused by flowing liquid metals in the outer core of the planet which causes electric currents and a magnetic field.

Other objects in the solar system are discussed in this online textbook viz. asteroids, meteorites, comets and dwarf planets.

Overview of animal and plant cells. Topics include cell walls, vacuoles, chloroplasts, peroxisomes, lysosomes, mitochondria, etc.