16.How are rocks grouped within each unit of geologic time similar? 17. A unit of geologic time is usually characterized by
of a dominant life-form.
18. What does the abbreviation Ma stand for?
19. When did Precambrian time begin?
20. What species were common during the Cambrian Period?

common management practices in dairy and poultry farming are: (i) proper shelter facilities and their regular cleaning. (ii) some basic hygienic conditions such as clean water, nutritious food, etc. (iii) animals are kept in spacious, airy, and ventilated place.

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.

several tissues working together form an organ, and several organs together make up an organisms.

the group of cell that carries out special jobs are tissue.