Diffusion does not require any energy because it occurs down a concentration gradient. This means it goes from one side which has a high concentration of a particular molecule, to another side with a low concentration of this molecule. This is a passive act, requiring no energy input from the cell because it simply equalizes the concentrations of the molecules on both sides of a membrane. Simple ion channels are in place for diffusion, and the molecule diffuses to the less concentrated side simply and without the need for ATP being broken down for energy.
Active transport on the other hand, does exactly the opposite. Molecules to be actively transported will go from a side in which they are less concentrated to a side in which there is already a high concentration of them, so against the concentration gradient. This process requires energy- if you think of cramming more objects into an already stuffed room, more energy and force is needed to push them into that crowded space.
Active transport therefore requires energy in the form of ATP to be released for the transport to take place, and is usually mediated via special transport channels which bind the molecule and transport it to the other side, with the cost of ATP being broken down to release energy.
To visualize this: it is easier to go down a slide, than it is to climb up it. Molecules in diffusion slide down the slide to the other side, but have to be actively transported up the slide by a helper (transport channel), with energy.
Matter is anything that is made of atoms and has mass
Climate change
Greenhouse effect
Some heat energy from the Earth’s surface escapes into space. If too much heat energy escaped, the planet would be very cold. However some gases in the atmosphere can trap escaping heat energy, causing some of it to pass back to the surface.
These are called greenhouse gases, and they keep our planet warm, which is a good thing. Carbon dioxide is an important greenhouse gas.
Increasing carbon dioxide levels
Humans burn fossil fuels such as oil, coal and natural gas. The energy released is used to power cars and other machines, to generate electricity, and to keep buildings warm. The burning fuel releases waste gases, including carbon dioxide. As the human population increases, more fuel is used, and more carbon dioxide is released.
Global warming
The extra carbon dioxide increases the greenhouse effect. More heat is trapped by the atmosphere, causing the planet to become warmer than it would be naturally. The increase in global temperature this causes is called global warming.
Mutation is a source but it is not the main source after it comes recombination in which 2 chromosomes with “normal” survival are taken from natural population of Drosophila and combined. Then comes immigration of genes in which the new chromosome mix in with different gene frequencies.
Answer:
velocity = 3 m/s
Explanation:
kinetic energy = 1/2 * mass(kg) * velocity²
Using the formula:
18 = 1/2 * 4 * velocity²
9 = velocity²
velocity = 3 m/s
