Unit 10 - Origins
Content
- MYP10u10.1 - The structure of the universe
- MYP10u10.2 - Structure of the Earth
- MYP10u10.3 - Gravity, the Sun and Moon
- MYP10u10.4 - The origins of life
- MYP10u10.5 - Asexual and sexual reproduction
- MYP10u10.6 - Males and females
- MYP10u10.7 - Animal reproduction
- MYP10u10.8 - Population and over-population
- MYP10u10.9 - Contraception
Scheme of work
The structure of the universe
The universe is big...
- Earth and moon
- Planets, planetoids, asteroids and the solar system
- The sun
- Other suns
- The Galaxy and milky way
- The universe
Structure of the Earth
Our observable Earth is what we see on the surface, continents, countries, seas and oceans. We observe that the geography of our planet is variable with many different ecosystems, ranging from tropical rainforests to deserts, oceans to icy wastes.
It is up to us to try and explain this variation and various theories have been proposed historically.
How do scientists arrive at theories? On what do they base their ideas?
Historical ideas
Let's consider some historical theories about the stucture of the Earth, Sun, Moon and planets.
1. The Earth is a flat disc with a roof made of holes through which light shines.
2. The Sun is a fiery chariot ridden across the sky by a god called Apollo.
3. The Earth is a sphere at the centre of everything and everything revolves around it.
4. The Sun is at the centre of everything and we orbit around it.
5. The moon is made of green cheese.
How can science help us to address these questions?
Our current model
The earth is thought to consist of several layers of matter. Why do we think this?
- Solid core made of an iron/nickel alloy
- molten outer core consisting of liquid iron/nickel
- The mantle, consisting of very hot soft rock
- The crust (where we live)
Gravity, the Sun and Moon
The Earth's motion
The motion of all of the planets around the Sun is kept in place by the force of gravity. This force acts over vast distances and holds all of the structure of the universe together.
The Earth and all of the other planets orbit around the sun in elliptical orbits. An ellipse is like a slightly elongated circle.
This means that the Earth is further away from the sun during part of its orbit and closer during another part. This is responsible for hotter summers in the southern hemisphere.
The seasons
These are caused by the Earth rotation on a axis that is tilted. This means that the northern hemisphere is closer to the sun during June than it is during December.
This causes the seasons.
Moons
Many of the planets have moons, although not all. The Earth is locked into rotation with our moon and always faces the same side.
The moon is lit up by sunlight giving rise to the phases of the moon.
Many of the other planets also have moons. Mars has two, Phobos and Deimos, while Saturn and Jupiter have many moons.
Tides
The rotation of the moon around the Earth causes the tides. There are two high tides and two low tides per day. The Sun's gravity also has an effect on the tides, but this is less powerful. When the two effects, Sun and Moon act together, this gives rise to very high tides (Spring tides).
The origins of life
Asexual and sexual reproduction
Males and females
Animal reproduction
Population and over-population
Contraception