New York State Chemistry RegentsNew York State Earth Science Regents

 
NYS Living Environment Regents August 2010
Living Environment Regents August 2010 Question 37 PDF Print E-mail
NYS Living Environment Regents August 2010
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Correct answer: (4) They result without the union of gametes.

All these organisms reproduce by budding or by binary fission. Budding is an asexual means of reproduction in which outgrowths from the parent form and pinch off to live independently or else remain to eventually form extensive colonies. This is exhibited by the sea anemone (1st organism in the illustration) and yeast (3rd organism in the illustration).  Binary fission occurs in amoeba (2nd organism in the illustration), wherein cells divide by mitosis. The union of gametes only occurs during sexual reproduction.

Incorrect answers:

(1) They vary genetically from the parent.

Any type of asexual reproduction produces genetically identical offspring.

(2) They are produced by the union of gametes.

Union of gametes only occurs during sexual reproduction.

(3) They obtain nourishment from a placenta.

Through sexual reproduction, fertilized mammals form a fetus, which are stored inside the body of the female parent during the embryonic development. Oxygen and nutrients are supplied to the fetus inside the mother through the organ called the placenta. A placenta is absent in the given species above.
 
Living Environment Regents August 2010 Question 34 PDF Print E-mail
NYS Living Environment Regents August 2010
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Correct answer: (2) meiosis

Structure X represents an ovum, the female gamete of humans. Gametes divide by meiosis, which is a two-stage type of cell division in sexually reproducing organisms that results in gametes with half the chromosome number of the original cell.

Incorrect answer:

(1) mitosis

Mitosis is another type of cell division in eukaryotic cells conventionally divided into the growth period and another four stages. These stages maintain the chromosome number by equally allocating replicated chromosomes to each of the daughter cells. Only meiosis occurs in sex cells or gametes, except for plants.

(3) recombination

Genetic recombination occurs during prophase I of meiosis, specifically during the chromosomal crossover of homologous chromosomes

(4) cloning

Cloning is the process of producing an individual organism with the same genetic makeup with another individual.
 
Living Environment Regents August 2010 Question 31 PDF Print E-mail
NYS Living Environment Regents August 2010
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Correct answer: (1) Cell division is most rapid at 37o C between 6 and 8 hours after it began.

A bacterial growth curve can be divided into four phases-lag, exponential, stationary, and death. During the lag stage, the bacteria are just introduced in the medium, which means the bacteria are still maturing and are not yet capable of division. When they start to divide, the exponential phase starts (steep slope), characterized by cell doubling. During this phase, the bacteria divide at a maximum rate until the nutrients become depleted. When the microbial count remains constant (horizontal line), it has reached the stationary phase. The last phase starts when the microbial count starts to go down again.

In the given bacterial curves, the exponential phase started at 2 hours after the culture was placed in the medium under 37oC, and stopped dividing after the 10th hour. Most rapid cell division occurred during the 6th to 8th hour, as illustrated by the steep slope of the curve.

Incorrect answers:

(2) Cell division is most rapid at 25oC between 20 and 24 hours after it began.

At 25oC, cell division started on the 2nd hour and entered the stationary phase after the 16th hour. The fastest cell division occurred during the 12th hour, shown as the steepest slope of the curve.

(3) Cell division is most rapid at 18oC between 4 and 8 hours after it began.

At 18oC, cell division (exponential phase) started at the 2nd hour and stopped at the 20th hour. Fastest growth in number took place 14-16 hours after introduction of bacteria to the medium, shown in the curve as the steepest slope.

(4) Cell division occurs at the same rate no matter what the temperature.

This statement is false because the steepest slopes of the three curves are not located at the same part of the y axis (time).

 
Living Environment Regents August 2010 Question 20 PDF Print E-mail
NYS Living Environment Regents August 2010
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Correct answer: (1) delivery of sperm

Structure A refers to the vas deferens. During ejaculation, the sperm formed in the testes are propelled from the epididymis through the vas deferens, which are two ducts located from the scrotum around and behind the urinary bladder, where each joins a duct from the seminal vesicle.

Incorrect answers:

(2) production of gametes

The production of gametes occur in the male gonads or testes (testis, singular), which is composed of highly coiled tubes surrounded by several layers of connective tissue. In the illustration, the testis is the oblong-shaped structure where the vas deferens (structure A) is connected.

(3) production of hormones

The production of androgen, the principal male reproductive hormone, occurs in the testes (oblong-shaped structure at the bottom of the illustration, where structure A is attached), particularly in the interstitial cells of Leydig.

(4) excretion of urine

Urine excretion is not a function of the reproductive system. The organs, though, are interconnected because in males, urine and sperm both pass out through the urethra. However, structure A is not responsible for urine production. Urine is produced in the kidneys then passes through the urinary bladder, which is the large funnel-like structure in the upper part of the illustration.
 
Living Environment Regents August 2010 Question 18 PDF Print E-mail
NYS Living Environment Regents August 2010
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Correct answer: (4) toxins in the bloodstream of the mother

Cigarettes contain nicotine, carbon monoxide and tar that can be distributed to the bloodstream through smoking or secondhand smoke. These toxins may prevent the flow of oxygen from the mother to the baby.

Incorrect answers:

(1) decreased digestive activity in the stomach of the fetus

The fetus is not yet capable of digestion. It receives nutrition from the mother through the placenta, which is a combination of maternal and embryonic tissues that transport nutrients, respiratory gases, and wastes to and from the fetus.

(2) a decrease in the amount of oxygen in the ovary of the mother

Though it is true that there would be a decrease in the amount of the oxygen transported to the fetus when a mother smokes, it is not true that respiratory gases like oxygen passes through the ovary. Respiratory gases are transported to the fetus through the placenta.

(3) inhalation of secondhand smoke by the fetus

The fetus is incapable of inhaling air yet. It receives respiratory gases from the blood of the mother through the placenta.
 
Living Environment Regents August 2010 Question 17 PDF Print E-mail
NYS Living Environment Regents August 2010
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Correct answer: (4) decreased biodiversity within species

The asexual reproduction exhibited by animals, like some genera of fishes, amphibians, and lizards, is called parthenogenesis. It is a process in which the egg develops without being fertilized. Sharks undergo a complex form of parthenogenesis that involves the doubling of chromosomes after meiosis to create diploid offsprings. Since crossing over of chromosomes did not occur between two different individuals, there is no recombination of genetic material that is responsible for diversity among species.

Incorrect answers:

(1) increased gene recombinations

No genetic recombination occurs during the asexual reproduction because there is no crossing over of chromosomes between two different individuals.

(2) increased number of males produced

During parthenogenesis in sharks, all the offsprings produced are females due to their X-Y sex-determination system, wherein female chromosomes are represented as XX. Thus, no male sharks (with XY chromosome) will be conceived due to the absence of Y chromosome.

(3) decreased number of eggs used

During asexual reproduction, eggs are still used. The eggs turn into diploid offsprings when the chromosomes double after meiosis. Thus, there is no change in the number of eggs used during reproduction.
 
Living Environment Regents August 2010 Question 13 PDF Print E-mail
NYS Living Environment Regents August 2010
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Correct answer: (3) development influenced by the environment

Phenotype, the physical and physiological traits of an organism, is influenced by the genotype (genetic makeup of the organism) and the environment. In given situation, the growth of the salamander was influenced by the surrounding, which is not favorable for its development.

Incorrect answers:

(1) the production of gametes

Gametes are haploid sex cells (egg or sperm) that unite during fertilization. Gametogenesis or the production of gametes is not exemplified in the given situation.

(2) faulty genes found in aquatic organisms

The genetic makeup of organisms could be changed through mutation. However, mutation is not exhibited in the given situation. The genes were not properly expressed due to the unfavorable condition of the environment.

(4) the production of new organism by environmental engineering

There is no such thing as environmental engineering where a new organism can be developed by the alteration in the environment. An organism can develop better traits by transferring the gene of interest from one organism to another through genetic engineering technology.
 
Living Environment Regents August 2010 Question 11 PDF Print E-mail
NYS Living Environment Regents August 2010

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Correct answer: (2) Increased concentration of glucose in leaf cells

Photosynthesis is the conversion of light energy, water, and carbon dioxide (CO2) into oxygen and chemical energy in the form of glucose, which is then to be stored or distributed to the different parts of the plant. Thus, when more carbon dioxide is used up, more glucose is produced as well.

Incorrect answers:

(1) Increased use of starch in root cells

During photosynthesis, carbon dioxide (CO2) and water is converted to glucose and oxygen through the use of light energy. Thus, sugar, such as starch, is not used up during the process. Sugar, together with oxygen, is used up during respiration.

(3) Increased ATP in root cells

ATP or adenosine triphosphate is the energy currency of cells. Energy is stored in the cells in the form of glucose. Thus, the energy formed after photosynthesis is not found as ATP, but as glucose molecules.

(4) Decreased concentration of oxygen in leaf cells

Plants produce their own food through the conversion of carbon dioxide (CO2), water, and sunlight into glucose and oxygen. Since this is a chemical reaction, then it must follow the rule that the reactants and the products must be in equilibrium. When carbon dioxide (reactant) is increased, the products, oxygen and glucose, must also increase.

 

 
Living Environment Regents August 2010 Question 08 PDF Print E-mail
NYS Living Environment Regents August 2010
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Correct answer: (2) cells and tissues

Each step represents the following embryonic stages of animals:

1-unicellular zygote

2, 3, and 4-multicellular cleavage

5-blastula formation

6-gastrulation

7-organogenesis

The initial stage of the embryogenesis is the zygote or the unicellular fertilized egg. This then undergoes several divisions forming tissues in a particular fashion until it reaches the 7th stage, the organogenesis, wherein the cells undergo differentiation to forms structures that will serve as the organs of the organism.

Incorrect answers:

(1) cells and organs

Cell is the basic unit of life. When cells aggregate for a specific function, it becomes a tissue. When tissues work together, these are now called organs. When the unicellular zygote divides, and the cells function together, it is then called a tissue.

(3) tissues and organelles

Tissues are collections of cells that work together for a specific function, while organelles are the membrane-enclosed parts of a cell. Though both of these structures are present in the stages illustrated, this answer is incorrect because cells must also be included in the structures present.

(4) organelles and cells

Organelles are parts of a cell with a specific function, while cells are the basic unit of life. The illustration exhibits stages wherein the cells are grouped together to form a specific task, thus, tissues are already present in those stages.
 
Living Environment Regents August 2010 Question 03 PDF Print E-mail
NYS Living Environment Regents August 2010

Correct answer: (3) Each of these cells contains only half the genetic information necessary for the formation of an offspring.

There are two types of cells in the body, the body cells and the sex cells. Body cells divide by mitosis, while sex cells divide by meiosis. A sex cell undergoing different stages of meiosis is illustrated. This division results in gametes with half the chromosome number of the original cells. When this gamete (sperm) unites with another gamete (egg) through fertilization, their genes would combine to form the genetic information of an offspring.

Incorrect answers:

(1) The cells are produced by mitosis and contain all the genetic information of the father.

Mitosis is a process of cell division that conserves the chromosome number of the original cells by equally allocating replicated chromosomes to each of the daughter cells.

(2) If one of these cells fertilizes an egg, the offspring will be identical to the father.

During fertilization, the haploid gametes (egg and sperm) unite and form a diploid offspring. The genes of the gametes are combined, thus the offspring has a new set of genetic information.

(4) An egg fertilized by one of these cells will develop into a female with the same characteristics as the mother.

When two gametes unite through fertilization, their genes also combine, forming an offspring with a different set of genetic information.
 


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