Evolution- 4.3 Species

Question 1

What is the main criterion used to define a species in organisms that reproduce sexually?

Answer 1

A species is defined by the ability of its members to interbreed and produce fertile offspring.

Question 2

What is a hybrid in terms of species reproduction?

Answer 2

A hybrid is the offspring produced through the sexual reproduction of two different species.

Question 3

How are species that reproduce asexually, like bacteria, defined since they cannot interbreed?

Answer 3

Species that reproduce asexually cannot be classified by interbreeding criteria. They are instead defined by other criteria, such as morphological or biochemical similarity.

Question 4

What role does morphological similarity play in defining a species?

Answer 4

Members of a species often share similarities in appearance, but morphological similarity alone does not necessarily define a species.

Question 5

What biochemical criteria are used to help define a species?

Answer 5

Members of the same species have greater similarity in their DNA base sequence and amino acid sequence than members of different species.

Question 6

What is meant by members of a species sharing a common gene pool?

Answer 6

Members of the same species share a common gene pool, meaning they can interbreed and exchange genes, while different species are reproductively isolated and have separate gene pools.

Question 7

Why can’t the ability to interbreed be used to define asexual species like bacteria?

Answer 7

Asexual species, like bacteria, reproduce through binary fission, so they do not interbreed, requiring different criteria for species classification

Question 8

What are reproductive isolating mechanisms?

Answer 8

Barriers that prevent two populations from interbreeding to produce fertile offspring, maintaining distinct species.

Question 9

What are pre-zygotic mechanisms?

Answer 9

Mechanisms that prevent the formation of a zygote by stopping fertilization before it occurs.

Question 10

What is temporal isolation?

Answer 10

Temporal isolation occurs when species reproduce at different times, preventing interbreeding.

Question 11

What is behavioral isolation?

Answer 11

Behavioral isolation is when differences in mating behaviors prevent mate recognition between males and females of different species.

Question 12

What is mechanical isolation?

Answer 12

Mechanical isolation occurs when anatomical differences between species prevent successful mating.

Question 13

What is gamete isolation?

Answer 13

Gamete isolation occurs when gametes from two species come into contact but cannot fuse, or the female reproductive tract is unsuitable for the male gametes.

Question 14

What are post-zygotic mechanisms?

Answer 14

Mechanisms that prevent hybrids from developing into fertile adults after fertilization.

Question 15

What is hybrid inviability?

Answer 15

Hybrid inviability occurs when hybrids fail to develop to reproductive maturity.

Question 16

What is hybrid sterility?

Answer 16

Hybrid sterility occurs when hybrids develop into adults but cannot reproduce due to issues like producing no gametes or having incompatible chromosomes.

Question 17

What are the sources of genetic variation during gamete production in sexually reproducing species?

Answer 17

Genetic variation arises from crossing over during prophase I, and independent assortment during metaphase I, both contributing to new combinations of genes.

Question 18

How does random fertilization contribute to genetic variation?

Answer 18

Random fertilization occurs when the fusion of sperm and egg is random, creating unique combinations of genetic material in offspring.

Question 19

How does mutation contribute to genetic variation?

Answer 19

Mutation introduces new variations or changes in DNA base sequences, leading to genetic diversity in a population.

Question 20

What is a gene pool?

Answer 20

A gene pool is the total sum of all genetic information within an interbreeding population.

Question 21

Why is a large gene pool important for survival?

Answer 21

A large gene pool provides genetic diversity, increasing the population’s ability to survive environmental changes and reducing the risk of extinction.

Question 22

How does natural selection lead to evolution?

Answer 22

Natural selection causes changes in allele frequency over generations, favoring traits that offer a survival advantage, resulting in evolutionary changes.

Question 23

What determines which traits are passed on through natural selection?

Answer 23

Traits that provide an advantage under selective pressures are more likely to be passed on to future generations, increasing in frequency within the gene pool.

Question 24

What is genetic drift?

Answer 24

Genetic drift is the random change in allele frequencies within a population due to chance events, not environmental selection pressures.

Question 25

How does genetic drift affect smaller populations?

Answer 25

Genetic drift has a more pronounced effect on smaller populations, reducing genetic diversity and increasing the risk of extinction.

Question 26

What are examples of events that can cause genetic drift?

Answer 26

Events like bushfires, hunting, hurricanes, and flooding can cause genetic drift by reducing the population size and altering allele frequencies.