Living Environment Regents Review Practice Evolution Change Over Time Question 11
Friday, 26 June 2009 07:53
During synapsis, chromatids in homologous pairs of chromosomes often twist around each other, break, exchange segments, and rejoin. This process usually contributes to
A)The formation of polyploid offspring
B)Nondisjunction of homologous chromosomes
C)Production of identical twins
D)Increased variability in offspring
Correct Answer: Option D - Increased variability in offspring
The concept described in the question is crossing-over. It is one way that increases variety in offspring. It occurs during meiosis when the replicated homologous chromosomes are in close contact with each other during synapsis. Hence, Option D is the correct answer.
Polyploid is a heritable condition of possessing more than B complete sets of chromosomes.
Nondisjunction is the failure of chromosome pairs to separate properly during cell division.
Also synapsis does not ensure the production of identical twins.
Synapsis does not contribute to any of the outcomes of the options A, B and C. Hence, they are incorrect.
Living Environment Regents Review Practice Evolution Change Over Time Question 12
Friday, 26 June 2009 07:54
A child is born with an extra chromosome in each of its cells. This condition is usually the result of
Correct Answer: Option A – Nondisjunction
Nondisjunction is the result of the paired homologous chromosomes separating unequally during meiosis. So instead of one of a particular chromosome going to each of the D resulting sex cells, one cell gets two chromosomes of that type. Then during fertilization that zygote gets three of that particular chromosome instead of the normal two, resulting in one extra chromosome. That zygote then undergoes mitosis, resulting in all the cells of that organism containing one extra chromosome.
Crossing Over is a process occurring during meiosis wherein two chromosomes pair up and exchange segments of their genetic material.
Segregation is an act of division.
Hybridization is the process of combining different varieties or species of organisms or to create a hybrid.
Hence, options B, C and D do not contribute to an extra chromosome in a cell and these options are incorrect.
Living Environment Regents Review Practice Evolution Change Over Time Question 13
Friday, 26 June 2009 07:56
The first life-forms to appear on Earth were most likely
A)Complex single-celled organisms
B)Complex multicellular organisms
C)Simple single-celled organisms
D)Simple multicellular organisms
Correct Answer: Option C - Simple single-celled organisms
Single celled organisms can survive in high temperatures, extremely dry or humid climates. They could easily survive and evolve. Hence, these were the organisms which were the first life forms on earth.
Complex single-celled organisms evolved from simple single-celled organisms and they lead to the evolution of simple multicellular organisms and then the complex multicellular organisms.
Living Environment Regents Review Practice Evolution Change Over Time Question 14
Friday, 26 June 2009 07:58
Which statement best explains the significance of meiosis in the process of evolution within a species?
A)The gametes produced by meiosis ensure the continuation of any particular species by asexual reproduction.
B)Equal numbers of eggs and sperm are produced by meiosis.
C)Meiosis produces eggs and sperm that are alike.
D)Meiosis provides for variation in the gametes produced by an organism
Correct Answer: Option D - Meiosis provides for variation in the gametes produced by an organism
Evolution can take place when there is variation helping adaption to the changes in the environment. And meiosis is the process which helps variation by dividing the parent cell into B daughter cells with half the number of chromosomes of the parent cell. Hence, Option D is the correct answer.
Gametes are involved in sexual reproduction.
Meiosis leads to the production of various egg cells in the female reproductive organ and various sperm cells in the male reproductive organ.
Living Environment Regents Review Practice Evolution Change Over Time Question 16
Friday, 26 June 2009 08:00
As a result of sexual reproduction, an organism can pass a gene mutation to its offspring if the mutation occurs in
A)A body cell
D)White blood cells
Correct Answer: Option C - A gamete
In the process of sexual reproduction gametes are the cells which fuse to form a zygote which grows into the organism. Hence, mutations in one organism can be passed to the offspring only if it occurs in the gamete.
Mutated body cells only live in the body of that organism and cannot be transferred through sexual reproduction.
Liver tissue is not involved in sexual reproduction and mutation of this cannot be transferred to a sexually produced offspring.
White blood cells are the defenders of the body from external agents. Mutated white blood cells can protect the organism in which they exist but cannot be passed to offspring through sexual reproduction.
Living Environment Regents Review Practice Evolution Change Over Time Question 17
Friday, 26 June 2009 08:01
Which concept is not a part of the theory of evolution?
A)Present-day species developed from earlier species.
B)Some species die out when environmental changes occur.
C)Complex organisms develop from simple organisms over time.
D)Change occurs according to the needs of an individual organism to survive.
Correct Answer: Option D - Change occurs according to the needs of an individual organism to survive.
Theory of evolution suggests that environmental factors are uncontrollable and they change with time. As the changes in the environment occur the organisms which can adapt to these changes survive and evolve. Those organisms which cannot change and adapt to the changing environment become extinct.
Hence, the above statements that present-day species developed from earlier species, that some species die out when environmental changes occur and that complex organisms develop from simple organisms is true according to the theory of evolution.
Hence, the only statement which is not true according to the theory of evolution is the Option D.
Living Environment Regents Review Practice Evolution Change Over Time Question 20
Friday, 26 June 2009 08:07
One characteristic of mutations is that they usually
A)Are caused only by the events of mitosis
B)Do not occur at random
C)Result in different genetic sequences
D)Occur to meet the needs of a species
Correct Answer: Option C - Result in different genetic sequences
Mutations are changes to the nucleotide sequence of the genetic material of an organism. Mutations can be caused by copying errors in the genetic material during cell division, by exposure to ultraviolet or ionizing radiation, chemical mutagens, or viruses, or can be induced by the organism itself, by cellular processes such as hypermutation. Mutations occur randomly and do not always occur to meet the needs of a species.
Hence, Option C is the correct answer and options A, B and D are incorrect.
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