10 Great Evolutionary Innovations- Chapter 5 Flashcards
___________ ________ is a grave genetic disease, where red blood cells twist into a rigid sickle shape, which in turn cannot squeeze through small capillaries.
Sickle-cell anemia
In clonal reproduction, or virgin birth, one cell divides from two. Sexual reproduction is just the reverse, One cell (sperm) fuses with another (the egg) to form a single cell (fertilized egg). Two cells give rise to one cell, so sex is replication backwards in a sense.
True or False?
True
The large majority of animals as well as plants are obligately sexual, which means that they can only reproduce through _____.
Sex
Clone species like dandelions only arose thousands as opposed to millions of years ago, and are doomed to a shorter ______ of a species.
lifespan
Darwin was among the first to ponder and although he married his own first cousin which he had ten children with, he was mainly focused on outbreeding in genetics.
True or False?
True
The first step in sex is the fusion of two sex cells, sperm and egg. Each brings a single set of ____________ to the union, which gives the fertilized egg two complete sets. The two copies are rarely the same and the ‘good’ copy has the potential to mask the effects of the ‘bad’ version. This is the core principle behind hybrid vigour.
chromosomes
The second step in sex is the regeneration of sex cells, each with a single copy of every ____, this is the key step to sex, and the most difficult to explain.
Gene
The process known as _______, begins by duplicating all the chromosomes, to give four sets per cell. These are mixed and matched or recombined, to generate four entirely new _________, each one taking some from here and some from there. Recombination is the real heart of sexual reproduction.
meiosis
Chromosomes
The last step in sex is the cell divides in half, and the ________ divide themselves again, to produce a clutch of four ‘________’ cells, each with a single set of unique chromosomes.
daughters
granddaughter
The last step in sex is the cell divides in half, and the ________ divide themselves again, to produce a clutch of four ‘granddaughter’ cells, each with a single set of unique chromosomes.
daughters
The last step in sex is the cell divides in half, and the ________ divide themselves again, to produce a clutch of four ‘granddaughter’ cells, each with a single set of unique chromosomes.
daughters
(Same word)
August Weismann, the heir to Darwin, argued in 1904 that sex generates greater variation for _______ ________ to act on. This differs from Darwins thoughts greatly, it implies that the benefit of sex was not for the individual but for the population. The likelihood of “good” and “bad” combinations is the same, but through time the bad combinations are weeded out through _______ ________, leaving mostly good combinations.
natural selection
Bad combinations are just as harmful as good combinations are helpful, this means there is no net advantage or disadvantage for any individuals in any generation
True or false?
True
Sex can recreate unblemished individual by bringing together unmutated genes in the same individual. Lane uses an analogy from John Maynard Smith for two broken cars in the same capacity. One car has a faulty gearbox, and the other a broken engine, sex is a mechanic who fashions a working car by combining the functional parts. Unlike a wise mechanic though, sex also combines broken parts to produce an unworkable heap or junk. Sex is even-handed as always, and the individual benefits will be forever cancelled out by individual harm.
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Deleterious Mutations As An Evolutionary Factor was proposed in 1983, his theory makes two bold assumptions which still provoke resentment among arguing evolutionists:
•1) the mutation rate is rather _______ than most people suspected (there must be a number of deleterious mutations in every individual in every generation.)
•2) Most organisms are more or less resistant to the effects of single mutations.
Higher
