Unit 2 : Heredity and Evolutionary Theory

Question 1

Discuss the key contributions to evolutionary theories made by - and his predecessors

Answer 1

• In the beginning , europeans organized living things and inanimate objects into a ladder or hierarchy known as the Great Chain of Being and this was based on the visible similarities
• This system was still used when Linnaeus developed a new system. Linnaeus noted the similarities between humans , monkeys and apes and classified them together as Primates.
• Jean Baptiste Lamarack then suggested a theory of inheritance of acquired characteristics tiscs , for example Lamarack said giraffes had long necks because the first giraffe reached up for leaves and the neck was stretched and was passed on after
• Then Charles Lyell proposed a non religious theory that explained the variation in the earths surface
• Then Darwin introduced the theory of natural selection paired with Mendelian genetics

Question 2

Explain how natural selection works

Answer 2

• This is essentially a mechanism of evolution. Organisms that are more adopted to their environment are more likely to survive and pass on the genes that are helpful. but if their genes are less equipped for the specific environment they are in, those genes might dissapear slowly in the gene pool

Question 3

Compare and Contrast the two types of cell division

Answer 3

1. Mitosis
   - All chromosomes in the nucleus of a cell replicate forming a double complement. Then the cell divides into two exact replicas with the exact same set of chromosomes and genes as the original.
2. Meiosis
   - this includes sex cells called gametes and they are sperm for males and egg cells for females.
   - When cells divide here the new cell has only half the number of chromosomes compared to their original cell.
   - The two gametes, sperm and egg must combine through fertilization

Question 4

Describe the basic structure of DNA and its replication

Answer 4

• The structure consist of double helix strand made of nucleotide bases , bases include, Thymine , Adenine , Cytosine and Guanine
• Replication occurs when the double helix is unzipped then starts where the start codon in the strand is and ends when it reaches the stop codon.

Question 5

Outline the basic concepts of heredity found in all sexually reproducing organisms

Answer 5

• There are different diploid numbers , for humans it is 46 chromosomes or 23 pairs , for horses it is 64 ( 34 pairs ) , for chimpanzees it is 48 ( 24 pairs ).
• Then each cell contains two variants of chromosomes, one from each parent , and they last pair is the one that tells us what the gender of the offspring is