mechanical weathering
Mechanical weathering is the process of breaking big rocks into little ones. This process usually happens near the surface of the planet. Temperature also affects the land. The cool nights and hot days always cause things to expand and contract. That movement can cause rocks to crack and break apart.Mechanical weathering involves mechanical processes that break up a rock: for example, ice freezing and expanding in cracks in the rock.
Gametes are mature haploid cells, or sex cells. When gametes unite with others from the opposite sex in the form of fertilization they create a zygote which then forms an embryo etc. At the end of meiosis the gametes only have <u>half</u> the chromosomes of the organism (only one copy of DNA)
Answer: C. It allows gametes to have half the original number of chromosomes of the organism.
Nucleic acids<span> are long polymers of repeating </span>subunits<span> called nucleotides. Each nucleotide is made </span>up<span> of three smaller building blocks (Figure 17): Figure 17 The structure of a nucleotide and the formation of </span>nucleic acid<span> chains.</span>
A substance that speeds up a chemical reaction—without being a reactant—is called a catalyst. The catalysts for biochemical reactions that happen in living organisms are called enzymes. Enzymes are usually proteins, though some ribonucleic acid (RNA) molecules act as enzymes too.
Enzymes perform the critical task of lowering a reaction's activation energy—that is, the amount of energy that must be put in for the reaction to begin. Enzymes work by binding to reactant molecules and holding them in such a way that the chemical bond-breaking and bond-forming processes take place more readily.
