Background extinction refers to the normal extinction rate. These are species that go extinct simply because not all life can be sustained on Earth and some species simply cannot survive. Mass extinction is a widespread event that wipes out the majority (over 50%) of living plants and animals.
Correct answer looks like to me would be A. Because, if a sunflower has 34 chromosomes, when you split it up into x and y chromosomes, there will be 17 x chromosomes and 17 y chromosomes. Hope this helps!
Lyases
Lyases are class of enzymes that catalyzes reactions involving the formation of double bonds.
Lyases are class of enzymes that catalyzes the joining of C-C ( carbon to carbon), C-O (carbon to oxygen), and C-N (carbon to nitrogen) bonds by hydrolysis or oxidation. These bonds are usually held by the process of elimination which leads to the formation of new double bonds or cyclical molecules. Examples of lyases include; aldolase and adenylate cyclase.
Some of the major organelles include the nucleus, mitochondria, lysosomes, the endoplasmic reticulum, and the Golgi apparatus. Plant cells also include chloroplasts, which are responsible for photosynthesis.