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I. ii. iii. iv. A. B. C. D.. TEST CORRECTIONS 1/3 pts back if done correctly1/3 pts back if done correctly Multiple choice:Multiple choice: –Write question.

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Presentation on theme: "I. ii. iii. iv. A. B. C. D.. TEST CORRECTIONS 1/3 pts back if done correctly1/3 pts back if done correctly Multiple choice:Multiple choice: –Write question."— Presentation transcript:

1 i. ii. iii. iv. A. B. C. D.

2 TEST CORRECTIONS 1/3 pts back if done correctly1/3 pts back if done correctly Multiple choice:Multiple choice: –Write question –Look up answer in notes/book! –Clearly write letter for correct answer AND the answer itself –Be neat! Highlight, underline, indent, etc…

3 Short Answer Write questionWrite question Write # pts earned/#pts availableWrite # pts earned/#pts available –Example: “earned 2/8” Summarize your earned pts & incorporate new points into a complete, thorough answer.Summarize your earned pts & incorporate new points into a complete, thorough answer. –Underline or highlight the NEW points –Do NOT copy straight from the markscheme or you will not get pts –Make it MAKE SENSE, paragraphs, sentences!

4 5.4 Evolution 5.4 Evolution

5 REALLY cool site... http://www.johnkyrk.com/evolution.html

6 5.4.1 Define evolution cumulative change in the heritable characteristics of a population.cumulative change in the heritable characteristics of a population. –Small changes, upon small chgs, –Over many generations –Gene-controlled factors –NOT an individual!

7 Range of eye complexity in living mollusk species (left to right): a pigment spot, as in the limpet Patella; a pigment cup, as in the slit shell mollusk Pleurotomaria; the "pinhole-lens" eye of Nautilus; a primitive lensed eye, as in the marine snail Murex; and the complex eye—with iris, crystalline lens, and retina—of octopuses and squids.

8 5.4.1 Define evolution 5 “sub theories” –Evolution: all life is and has been perpetually changing –Common descent: if traced back far enough,  all life has common ancestor –Gradualism: evol change is slow & gradual –Multiplication of species: speciation leads to diversity of life; pops adapt to locations, become reproductively isolated from other pops –Natural selection: produce genetic variation & select for/against

9 Explain evolution of a species by natural selection in response to environmental change.Explain evolution of a species by natural selection in response to environmental change. (Total 7 marks)

10 species show variation; variation is inherited; species have the potential to produce more offspring than can survive; this leads to a struggle for existence / survival; resources are limited; those that are best adapted (on average) survive to reproduce; this leads to a population adapted to the environment; as the environment changes those that are best adapted will leave more offspring; this will cause the species to evolve to a new adaptation / change in gene frequencies;species show variation; variation is inherited; species have the potential to produce more offspring than can survive; this leads to a struggle for existence / survival; resources are limited; those that are best adapted (on average) survive to reproduce; this leads to a population adapted to the environment; as the environment changes those that are best adapted will leave more offspring; this will cause the species to evolve to a new adaptation / change in gene frequencies; [7][7]

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15 5.4.2 Outline the evidence for evolution provided by the fossil record,...

16 PBS: Whales in the Making http://www.pbs.org/wgbh/evolution/l ibrary/03/4/quicktime/l_034_05.html http://www.pbs.org/wgbh/evolution/l ibrary/03/4/quicktime/l_034_05.html

17 5.4.2 Outline the evidence for evolution provided by the.. selective breeding... Selective Breeding: By Humans! (Art. Sel.) –Animals, plants selected for breeding b/c desirable traits  future generations w/higher freq of trait –Cows w/high milk yield –Dog breeds –Corn –Select for... –Select against...

18 5.4.2 Outline the evidence for evolution provided by... homologous structures. Analogous = not a recent common ancestor; convergent evo.

19 So, how does natural selection work?? ____________ & __________________

20 5.4.3 State that populations tend to produce more offspring than the environment can support.

21 More than needed to keep species around More than K can support, ltd resources Intraspecific competition –Some have competitive advantage (traits, behaviors, symbioses) More fit (competing for resources, fighting disease, etc.) = More likely to successfully reproduce Freq of these alleles higher in next generation

22 5.4.4 Explain that the consequence of the potential overproduction of offspring is a struggle for survival. Some individuals selected FOR, some selected AGAINST –Survivors (FOR) form new breeding population –Increases freq of advantageous alleles

23 5.4.5 State that the members of a species show variation. Populations show variation... differences in phenotypes! Varying forms of a trait... (flower color, teeth shape)

24 5.4.6 Explain how sexual reproduction promotes variation in a species.

25 MIXING IT UP w/MEIOSIS! Random asstmt of chromosomes in Metaphase I –2^n combinations of chroms in daughter cells –8,388,608 in humans!! Crossing-over in Prophase I –New combos of alleles on a chrom. Random fertilization  any gamete can fert any gamete from the other indiv

26 Other source of variation??Other source of variation?? MUTATIONSMUTATIONS


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