Which major processes were needed for the origin of life on Earth? Abundance of oxygen and the ozone layer
Active volcanoes and very cold temperatures
Low levels of ultraviolet radiation and specific mixture of gases
Organic molecules produced from spontaneous synthesis or from meteorites

What is the difference between self-pollination and cross-pollination? question 2 options: self-pollination leads to the creation of a fruit. cross-pollination does not. during cross-pollination, ovules are carried from one plant to another plant.. during self-pollination the ovules stay on the same plant. during cross-pollination, ovules are carried from one plant to another plant.. during self-pollination the ovules stay on the same plant. during cross-pollination the pollen grains are carried from one plant to another plant. during self-pollination the pollen and ovules are from the same plant. during cross-pollination, the pollen grains travel from the stigma to the anthers. during self-pollination, the pollen grains travel from the anthers to the stigma.

Elements and compounds are pure substances that cannot be broken down physically into a simpler substance. a physical change doesn’t break the bonds between atoms of a substance or form new ones. compounds can be broken down by a chemical change. a chemical change breaks chemical bonds and/or forms new ones between atoms of a substance. what simple substance would a compound break into? the basic elements that make it up! for example, if you passed a very strong electric current through water you’d break the chemical bonds in water and be left with oxygen and hydrogen. which of the following is an example of a chemical change? a separating water into different glasses b breaking frozen ice cubes with a hammer c running an electric current through water d boiling water to evaporate it on a stove

When new rock is added to an oceanic ridge, the magnetized strips on either side of the ridge are evidence of sea-floor spreading. this is because the rocks on the two sides of the ridge o are equal in width and in polarity are polar opposites oare magnetized vary in width but are equal in polarity