Living Environment Regents Review Practice Heredity and Genetics Question 1
Friday, 26 June 2009 10:45
When a person’s limbs are being X-rayed other parts are covered with lead blanket to prevent
A)Changes in glucose structure
B)Decrease in cell size
C)Changes in DNA molecules
D)Loss of hair
Correct Answer: Option C – Changes in DNA molecules
X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays have a wavelength in the range of A0 to 0.0A nanometers. X-rays are primarily used for diagnostic radiography and crystallography. As a result, the term X-ray is metonymically used to refer to a radiographic image produced using this method. X-rays can be dangerous.
Too much radiation at one body site can cause skin conditions resembling severe burns or local cancers. If excess radiation strikes the gonads (ovaries or testicles),it can cause mutations in the genes, which in turn, may mean deformities in the patient's descendants.
Hence, option C is the correct answer.
Exposure to X-rays does not cause changes in glucose structure, decrease in cell size or loss of hair. Hence, options A, B and D are incorrect.
Living Environment Regents Review Practice Heredity and Genetics Question 2
Friday, 26 June 2009 10:47
One molecule of DNA is a polymer composed of
Correct Answer: Option C - Nucleotides
DNA is composed of nucleotides which are linear and contain a phosphate group, a five carbon sugar called deoxyribose and a nitrogenous base. Hence, option C is the correct answer.
Fatty Acids are one of many molecules that are long chains of lipid-carboxylic acid found in fats and oils and in cell membranes as a component of phospholipids and glycolipids. Carboxylic acid is an organic acid containing the functional group -COOH. Hence, option A is incorrect.
Amino Acids are building blocks of proteins and act as intermediates in metabolism. Hence, option B is incorrect.
Sugars are elements of food which when digested provide energy to the body. Hence, option D is incorrect.
Living Environment Regents Review Practice Heredity and Genetics Question 4
Friday, 26 June 2009 10:50
Chromosomes occur as homologous pairs in
Correct Answer: Option A – A Zygote
A zygote is the fertilized egg formed by the combination of B gametes (sperm and egg cells). Each gamete provides the zygote half of the genetic information. This genetic material completes the new cell formed called zygote with homologous pairs. Hence, option A is correct.
A gamete is a cell providing half of the genetic material for the formation of a zygote in which chromosomes do not occur as homologous pairs. Hence, option B is incorrect.
Egg and sperm cells are gametes which have half of the genetic material. Hence, options C and D are incorrect.
Living Environment Regents Review Practice Heredity and Genetics Question 5
Friday, 26 June 2009 10:52
How many chromosomes do human beings have?
Correct Answer: Option C – 23 pairs
A Chromosome is a long DNA molecule and associated proteins that carry portions of the heredity information of an organism. Human Beings have 21 homologous pairs chromosomes totaling to 46 chromosomes, divided into 22 pairs of autosomes and 1 pair of sex chromosomes.
Living Environment Regents Review Practice Heredity and Genetics Question 9
Friday, 26 June 2009 14:31
Choose a statement that describes the result of some of the processes involved in genetic engineering
A)The processes are necessary for normal gamete formation.
B)The processes provide energy for mitosis and meiosis.
C)The processes alter the arrangement of hereditary material.
D)The processes reduce variation in organisms which produce asexually.
Correct Answer: Option C - The processes alter the arrangement of hereditary material.
Genetic engineering is different from traditional breeding, where the organism's genes are manipulated indirectly. Genetic engineering uses the techniques of molecular cloning and transformation to alter the structure and characteristics of genes directly. Hence, option C is correct.
Genetic engineering is not involved in gamete formation or provision of energy for mitosis and meiosis or reduction in variation of organisms which produce asexually.
Living Environment Regents Review Practice Heredity and Genetics Question 10
Friday, 26 June 2009 14:32
Which element of a cell helps a parent to transfer the genetic information to the offspring?
Correct Answer: Option C – DNA
DNA provides the set of coded instructions required by every organism for specifying its traits. Hence, the DNA molecule provides for a reliable way for parents to pass their genetic code from one generation to the next.
Cell Membrane is the outer cover of the cell and does not help in transmitting genetic information. Hence, option A is incorrect.
Cytoplasm is a substance that fills the cell. Hence, option B is also incorrect.
Mitochondria are the power sources of the cell and are not involved in transmission of genetic information from one generation to another.
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