Chapter 26:ans EVEN

2) O₂

4) intense UV bombardment

6) H₂.

8) The early Earth was intensely bombarded by large space debris.

10) The proportion of the amino acids are similar to those produced in the Miller-Urey experiment.

12) a surrounding membrane or membrane-like structure

14) self-replicating, catalytic RNA molecules.

16) DNA is chemically more stable and replicates with fewer errors (mutations) than RNA.

18) Natural selection favored RNA molecules that synthesized catalytic proteins.

20) the accumulation of the daughter isotope the loss of parent isotopes

22) 3,500,000,000 years

24) 3, 2, 1, 4

26) O₂

28) e^- + H⁺ + O₂ → H₂O, alpha proteobacteria

30) infolding of the plasma membrane

32) nucleus

34) consists of protein subunits synthesized by ribosomes within the mitochondria. consists of protein subunits synthesized by ribosomes in the surrounding cytoplasm. is a component of a metabolic process that requires oxygen as a final electron acceptor.

36) horizontal gene transfer

38) 4, 1, 3, 2, 5

40) Cambrian explosion

42) a zygote. a sperm cell. an egg cell. a mother cell about to undergo meiosis.

44) a net loss of intertidal zone and coastal habitat.

the extinction of species adapted to intertidal and coastal habitats.

an overall increase in the surface area located in the continental interior.

an increase in climatic extremes in the interior of the new supercontinent.

46)molecular

48) It was used for organisms that did not fit clearly into the other two kingdoms.

50) 5

52) 5

54) 1, 4, and 5

56) a

58) e

60) Precambrian.

62) formation of oxygen

64) They are sedentary