Stuff you need to know…. Genetics. Meiosis- cell division that forms gametes (sex cells sperm or egg ) Will form 4 genetically different cells Haploid- 1 copy of the chromosomes (gametes), human haploid #= 23
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Stuff you need to know…
Sex-Linked Genes: genes that are on the X or Y chromosome
*because any gene on the Y chromosome will always affect males & only males, these problems only discuss genes on the X chromosome
*females have 2 X chromosomes & males have 1 therefore, males are more likely to exhibit recessive phenotypes from sex-linked genes
TERMS TO KNOW!!
·EVOLUTION: cumulative change in the heritable characteristics of a population
(“CHANGE OVER TIME”)
·FITNESS: refers to traits and behaviors of organisms that enable them to survive and reproduce
·ADAPTATION: any inherited characteristic that enhances an organism’s ability to survive and reproduce in that particular environment
~based on variations randomly inherited (mutation & meiosis)
Not all organisms can survive
Overproduction occurs in nature
Variation occurs in all populations
Variations are inherited
Organisms with favorable variations survive and reproduce
Populations as a whole become FIT = evolved!
Changes in the gene pool (# or % of “A” allele vs “a” allele) of a small population due to chance; REDUCES VARIATION
-Bottleneck Effect: results from drastic decrease in population size
-Founder Effect: few individuals in a population colonize a new habitat
The origin of new species (the appearance of new species is the source of biological diversity)
1) Life is ORGANIZED on many structural levels:
Levels beyond the individual organism:
Energy flows through an ecosystem (a section of the biosphere) from the sun, to producers, to consumers
IN ONE DIRECTION!!!
Fossils-Any preserved evidence of life from a past geological age (ex: impressions & remains of organisms embedded in stratified rocks; mineralized remains of an animal or plant
Fossils include shells, imprints, burrows, and organically-produced chemicals. The oldest fossils are of bacteria (prokarytotes) & they are 3.8 billion years old.