GENETICS & HEREDITY In humans, the allele for dimples (D) is dominant. The allele for not having dimples (d) is recessive. A woman (DD) and a man (Dd) have four children. Which of these is the predicted ratio of the children with dimples to the children without dimples?

A. 1:0 B. 1:1 C. 1:3 D. 3:1

Correct Answer: A

In humans, the allele for unattached (free) earlobes (F) is dominant. The allele for attached earlobes (f) is recessive. A woman who is heterozygous for this trait marries a man who has attached earlobes. What is the probability that this couple's child will have unattached earlobes?

A. 25% B. 50% C. 75% D. 100%

Correct Answer: B

The presence or absence of freckles is determined by one gene. The allele for freckles (F) is dominant and the allele for the absence of freckles (f) is recessive.

A couple has several children. All of the children have freckles because their parents' genotypes can only produce children with freckles.

Which of these are most likely the genotypes of the two parents?

A. Ff and ff B. FF and ff C. Ff and Ff D. ff and ff

Correct Answer: B

In horses, the allele for straight hair (B) is dominant to the allele for curly hair (b). Which of these sets of parents can produce offspring with curly hair?

A. a heterozygous male with straight hair and a homozygous female with straight hair B. a homozygous male with curly hair and a homozygous female with straight hair C. a heterozygous male with straight hair and a heterozygous female with straight hair D. a homozygous male with straight hair and a homozygous female with straight hair

Correct Answer: C

Use the information and the table below to answer the following.

A group of students wanted to determine how the ability to taste PTC, a nontoxic chemical, is passed from one generation to the next. The students decided to test families in their community for this ability. The students gave each family member a paper strip coated with a small amount of PTC. Those who experienced the bitter taste of PTC when they touched the paper strips to their tongues were called "tasters"; those who could not taste the PTC were called "nontasters."

The results of the experiment are shown in the table below.

Which of these explains how two taster parents could produce a nontaster child?

A. Both parents are heterozygous and produce a homozygous recessive child. B. Both parents are homozygous recessive and produce a homozygous dominant child. C. Both parents are heterozygous and produce a heterozygous child. D. Both parents are homozygous dominant and produce a homozygous recessive child.

Correct Answer: A

In humans, the allele for long eyelashes is dominant (L) and the allele for short eyelashes is recessive (l). A female who is heterozygous for long eyelashes and a male with short eyelashes have a child.

What is the probability that their offspring will have short eyelashes?

A. 0% B. 25% C. 50% D. 75%

Correct Answer: C

In a species of plant, the allele for red flowers (R) is dominant to the allele for orange flowers (r). Red flower color in the plants is not sex-linked. Students crossed plants that had red flowers and recorded the flower color of their offspring. Their data are shown below.

Plant Offspring Flower Color Number of Offspring Red 77 Orange 27

What are the most likely genotypes of the parent plants?

A. RR and rr B. Rr and Rr C. rr and rr D. RR and Rr

Correct Answer: B

One kind of chromosomal abnormality can occur during meiosis when a pair of chromosomes that carry genes for the same trait fail to separate. Which of these represents the sex chromosomes of a male organism when this type of chromosomal abnormality has occurred?

A. XXY B. XX C. XY D. XXX

Correct Answer: A

The allele for attached earlobes (f) is recessive to the allele for unattached (free) earlobes (F). A woman with the genotype (Ff) and a man with the genotype (ff) have a child.

What is the probability that the child is heterozygous for attached earlobes?

A. 0% B. 25% C. 50% D. 75%

Correct Answer: C

Which of these is an example of a heterozygous genotype?

A. Rr B. RR C. wrinkled D. round

Correct Answer: A

Use the information and Punnett square below to answer the following question.

In guinea pigs, the allele for black fur (B) is dominant. The allele for brown fur (b) is recessive. Two guinea pigs were crossed as shown in the Punnett square below. Numbers 1, 2, 3, and 4 represent the types of offspring produced from the cross.

What is the probability that an offspring from this cross would have brown fur?

A. 0% B. 25% C. 50% D. 75%

Correct Answer: A

Use the information and Punnett square below to answer the following question.

In guinea pigs, the allele for black fur (B) is dominant. The allele for brown fur (b) is recessive. Two guinea pigs were crossed as shown in the Punnett square below. Numbers 1, 2, 3, and 4 represent the types of offspring produced from the cross.

Which of these describes the phenotypes of the parent guinea pigs?

A. Both parents have black fur. B. Both parents have brown fur. C. One parent has black fur, and the other has brown fur. D. One parent has a mixture of black and brown fur, and the other has black fur.

Correct Answer: A

One parent is homozygous dominant for brown hair (BB). The other parent is heterozygous for brown hair (Bb).

What is the probability that the offspring will have brown hair?

A. 100% B. 75% C. 50% D. 25%

Correct Answer: A

Red-green color blindness affects about 7.0% of the human male population. It affects approximately 0.4% of the human female population. These data suggest that red-green color blindness is a

A. dominant trait carried on the Y chromosome B. dominant trait carried on the X chromosome C. recessive trait carried on the Y chromosome D. recessive trait carried on the X chromosome

Correct Answer: D

In humans the trait of having freckles (F) is dominant to not having freckles (f).

Which genotype and phenotype are correctly paired?

A. FF—no freckles B. Ff—no freckles C. Ff—freckles D. ff—freckles

Correct Answer: C

How many nucleotides are needed to code for one amino acid?

A. 1 B. 3 C. 4 D. 6

Correct Answer: B

Which RNA sequence is produced using the DNA sequence AGC-TAC-ACT?

A. UCG-AUG-UGA B. UCG-UAC-ACU C. TCG-ATG-TGA D. AGC-UAC-ACU

Correct Answer: A

Hemoglobin is an important protein in red blood cells. The DNA code for hemoglobin contains the following segment:

TGC-GGA-CTC-CTC

Which of these is the messenger RNA code for this segment of DNA?

A. ACG-CCT-GAA-GAA B. TCC-GGT-CTC-CTC C. ACG-CCU-GAG-GAG D. UGC-GGA-CUC-CUC

Correct Answer: C

The diagram below shows the key steps for making proteins. (Use to answer the following TWO questions)

Which step involves transfer RNA?

A. I B. II C. III D. IV

Correct Answer: D

According to the diagram, in which step is messenger RNA being constructed?

A. I B. II C. III D. IV

Correct Answer: B

Look at the DNA sequence below.

GAA TTC GCA

What do the G and A represent in the DNA sequence?

A. sugars B. amino acids C. phosphates D. nitrogen bases

Correct Answer: D

Scientists have recently discovered a new species that lives attached to the side of a tree. An organism from this new species

is multicellular has cell walls has vascular tissues makes its own food has structures that absorb moisture from the air

The scientists learned that this organism produces a special protein that prevents it from freezing in cold weather. Which of these contains the information for making this protein?

A. a vacuole B. a lipid C. a vitamin D. a gene

Correct Answer: D

Which of the following is correctly matched with its function?

A. rRNA - contains codes to make new ribosomes B. DNA - carries the amino acids to the ribosomes C. tRNA - combines with proteins to make up ribosomes D. mRNA - carries genetic codes from nucleus to the ribosomes

Correct Answer: D

Which of these statements best explains how genes and proteins are related?

A. Genes are segments of DNA that code for proteins. B. Proteins are segments of DNA that code for genes. C. Genes are the building blocks of proteins. D. Proteins are the building blocks of genes.

Correct Answer: A

A strand of DNA has a nucleotide base sequence of TAC-CGG-AGT. Which of the following is the complementary mRNA nucleotide sequence produced from the strand of DNA?

A. UAC-CGG-AGU B. ACU-GAA-CGA C. AGU-UCC-UAC D. AUG-GCC-UCA

Correct Answer: D

A cellular process uses a strand of genetic material to produce a new strand. Parts of the strands are shown below.

Original strand ATT CAG

New strand UAA GUC

This new strand will most likely be used for

A. gene splicing B. DNA synthesis C. crossing-over D. protein synthesis

Correct Answer: D

The genetic information for making a protein must move from the nucleus to the cytoplasm. Which of these moves this information to the cytoplasm?

A. a ribosome B. DNA C. RNA D. an amino acid

Correct Answer: C

What is one role of transfer RNA in the cell?

A. preparing the genes for messenger RNA B. changing nitrogen bases into amino acids C. preparing messenger RNA for the ribosomes D. carrying amino acids to the ribosomes

Correct Answer: D

The nucleotide base sequence of a strand of DNA is TAC-CGG-AGT. What is the sequence of the complementary DNA strand?

A. TAC-CGG-AGT B. ACT-GAA-CGA C. AGT-TCC-TAC D. ATG-GCC-TCA

Correct Answer: D

Which of these make up the primary link between a gene and the expression of a trait?

A. proteins B. sugars C. lipids D. vitamins

Correct Answer: A

Which of these best describes the correct sequence in the expression of a trait?

A. trait → gene → enzyme B. gene → protein → trait C. protein → gene → trait D. gene → trait → DNA

Correct Answer: B

Use the information below to answer the following item.

Scientists genetically modified a variety of corn to protect it against pests like the corn borer. The corn borer is an insect caterpillar that feeds on the corn stalk, which weakens the stalk and makes it fall over. A new gene in the genetically modified corn causes the plant to produce a chemical that is toxic to the corn borer. Some people are concerned that the genetically modified corn could harm other insects such as the monarch butterfly caterpillar. The monarch caterpillar eats leaves of milkweed plants that might be coated with toxic corn pollen. However, not all researchers agree with the concerns regarding the monarch butterfly caterpillar. They state that it is unusual for large amounts of harmful corn pollen to be found on milkweed leaves. Also, only a small percentage of caterpillars feed on the milkweed plants near corn fields.

Which was most likely introduced into corn that made it pest-resistant?

A. gene B. lipid C. toxin D. protein

Correct Answer: A

Use the technical passage and drawing to answer the following TWO items

BOGTURTLES

One of the smallest turtles in the world is found along the east coast of the United States from Massachusetts to Georgia. The bog turtle, measuring only 100 millimeters in length, was unknown in Maryland before 1941. A drawing of a bog turtle is shown below.

Studies conducted in recent decades verified that Maryland was included in the range of the bog turtle. It was often misidentified because the colorful orange patterns on its head and neck resembled other turtles. To learn more about the bog turtle, scientists conducted a survey of its habitat sites. The results of the survey led to a more thorough investigation of bog turtle sites by the Maryland Department of Natural Resources. As a result, the number of sites increased from

one verified site in 1944 to 177 verified sites in 1984.

Known bog turtle sites are less than one acre in size. Bog turtles prefer to live in areas of low-lying wetlands, swamps, and meadows that are soft and muddy. These habitats aid in body temperature regulation and egg incubation. Ground water springs provide an area where the turtles can spend winter without the threat of freezing. The vegetation in the bog turtle habitat consists of cattails, sphagnum moss, and various native grasses. Although the bog turtle population may never have been large, habitats since precolonial times have declined because of development and changing farm practices.

The state of Maryland added the bog turtle to the list of endangered species in 1972. Steps to protect its habitat include land use management, bog preservation, private landowner cooperation, management of invasive plant species, as well as captive breeding programs. By adding federal protection to the existing protection provided at the state level, one of the smallest turtles in the world may continue to survive.

Which of these is responsible for the color patterns on the head and neck of the bog turtle?

A. carbohydrates B. diet C. habitat D. proteins

Correct Answer: D

Which of these processes would most likely cause new color patterns on the head and neck of bog turtles?

A. mitosis B. mutation C. succession D. replication

Correct Answer: B

An Olympic gold medalist in cross-country skiing has a gene which causes him to produce 50% more hemoglobin than the average person. Which of these most likely caused this trait?

A. a special diet designed for the skier B. the climate where the skier lives C. the training routine of the skier D. a mutation carried by the skier

Correct Answer: D

Which of these results when one nitrogen base replaces another in a segment of genetic material?

A. an enzyme substrate B. a mutation C. a feedback loop D. an adaptation

Correct Answer: B

A rare disorder is caused by changes in a gene. Parents of individuals with the disorder have only normal copies of this gene. Which of these most likely causes this disorder?

A. mitosis B. gene splicing C. mutation D. natural selection

Correct Answer: C

Use the information below to answer the following item.

A pair of laboratory mice are crossed to obtain offspring. Three alleles found in the female gamete are ABC. Three alleles found in the male gamete are Abc.

What is formed when a male gamete combines with a female gamete?

A. zygote B. egg C. sperm D. chromosome

Correct Answer: A

A scientist cloned a goat. Which of these is a true statement about the cloned goat?

A. It has new genes and traits. B. It lacks the genes for reproduction. C. It has genes that are identical to the original goat. D. It looks the same as the original goat but has different genes.

Correct Answer:

Two segments of DNA are shown in the diagram below.

Normal thymine (T) is found in the old strand. It is replaced by an abnormal molecule (T*) in the new strand. The abnormal molecule (T*) binds to guanine (G) instead of binding to adenine (A). This is an example of

A. an adaptation B. protein synthesis C. a mutation D. binary fission

Correct Answer: C

A scientist is trying to discover a new treatment to stop cancer cells from dividing. In the cancer cells, which of these processes will stop if the treatment is successful?

A. mitosis B. chemosynthesis C. binary fission D. genetic recombination

Correct Answer: A

Use the diagram of the two different organisms and the information below to answer the following.

Streptococcus is a type of bacteria that causes strep throat in humans. A frog is a multicellular organism that lives in aquatic environments.

Which of these is the type of reproduction used by Streptococcus?

A. binary fission B. meiosis C. crossing-over D. budding

Correct Answer: A

A protein called p53 can keep cells from dividing. To prevent cell division, this protein most likely stops

A. osmosis B. mitosis C. respiration D. mutation

Correct Answer: B

Cholera bacteria live inside copepods, tiny marine organisms. This type of microscopic bacteria harms the copepods by feeding off their internal tissues.

Both of these organisms are found in oceans throughout the world. Unfavorable temperatures or salt levels may cause cholera bacteria to become inactive. When inactive, they do not feed or reproduce. When conditions become favorable, they become active once again.

A cholera population may depend on the population of copepods in the surrounding water. A simple food chain showing this relationship is shown below.

Cholera bacteria perform binary fission to

A. reproduce asexually B. digest food rapidly C. regulate temperature D. increase body size

Correct Answer: A

A stutwo

Whic

ABCD

CorrA

Use

The

How

ABCD

CorrB

udent observcells, as sho

ch of these b

A. binary fisB. meiosis C. osmosis D. sexual re

rect Answer

the informat

diagram bel

w does the ch

A. half the nB. the sameC. twice theD. four time

rect Answer

ves a unicelluwn in the di

best describe

ssion

eproduction

r:

tion and the

low shows st

hromosome n

number of chnumber of c

e number of es the numbe

r:

ular organismagram.

es the proces

diagram bel

tages of cell

number of th

hromosomeschromosomechromosomeer of chromo

m under a m

ss shown in t

low to answe

division of a

he amoeba in

s es es

osomes

microscope. A

the diagram?

er the follow

an amoeba,

n stage 1 com

After a while

?

wing item.

a unicellular

mpare to an

e, the organi

r organism.

amoeba in s

ism begins to

stage 3?

o split into

Use

The

Scienstagecaus

Specprote

ABCD

CorrD

Aftezygo

ABCD

CorrC

the informat

diagram bel

ntists have fe 2 to stage 3ed during D

cialized proteeins?

A. mitochonB. nucleus C. pseudopoD. ribosome

rect Answer

r an egg cellote?

A. 8 B. 16 C. 32 D. 64

rect Answer

tion and the

low shows st

found that th3 is slowed bNA replicati

eins control

ndrion

od e

r:

l containing

r:

diagram bel

tages of cell

he rate of divby proteins. ion.

cell division

16 chromos

low to answe

division of a

vision in amoThe addition

n in the amoe

omes is ferti

er the follow

an amoeba,

oebas is contnal time seem

eba. Which

ilized, how m

wing item.

a unicellular

trolled. Scienms to help th

cell part is r

many chrom

r organism.

ntists believhe amoeba c

responsible f

mosomes will

ve that the trachange codin

for making th

l be present

ansition fromng errors

hese

in the

m

Use the information below to answer the following item.

Scientists determined that excess fertilizer from farms entered a shallow lake. The fertilizer caused an increase in aquatic plants in the lake and then a decrease in oxygen in the water. Next, organic debris collected on the bottom of the lake. Over several years, the lake gradually filled in with organic sediment.

One species of aquatic plant found in the lake has 84 chromosomes in each cell. As nutrient levels increased, the population of this species increased through vegetative reproduction (also known as runners). How many chromosomes were in the cells of the offspring?

1. 21 2. 42 3. 84 4. 168

Correct Answer: C

Use the information below to answer the following.

The largest flower in the world, called a rafflesia, is three feet wide and weighs up to 36 pounds. The rafflesia has no roots, stems, or leaves. It lives on and takes nourishment from a vine called tetrastigma. The rafflesia harms the vine.

The seeds of the rafflesia are dispersed in an unusual way. Plantain squirrels and tree shrews eat parts of the rafflesia plant. Scientists observe that when the animals chew the rafflesia, seeds get caught in their teeth. The animals will then chew on tetrastigma vines, leaving the seeds where they can germinate.

Specialized cells in the rafflesia flowers undergo a process that produces gametes. What is this process called?

A. binary fission B. meiosis C. fertilization D. enzyme regulation

Correct Answer: B

Which of these represents the number of chromosomes in cells before and after the process of meiosis?

A. n n B. n 2n C. 2n n D. 2n 2n

Correct Answer: C

Which of these describes a mutation that can be inherited?

A. random breakage in a liver cell's DNA B. abnormal lung cells produced by toxins in smoke C. a nitrogen base substitution in a gamete cell D. ultraviolet radiation damage to skin cells

Correct Answer: C

A sperm cell of a moth has 112 chromosomes. How many chromosomes are in the moth's wing cells?

A. 66 B. 112 C. 224 D. 448

Correct Answer: C

Reproductive cells are produced during

A. mitosis B. meiosis C. fertilization D. budding

Correct Answer: B

Which of these is produced as a result of fertilization?

A. a zygote with twice the number of chromosomes as a gamete B. an egg with half the number of chromosomes as a zygote C. a gamete with twice the number of chromosomes as a zygote D. a zygote with half the number of chromosomes as a gamete

Correct Answer: A

Corals are marine animals that often live in tropical seas. Many types of corals have unicellular algae living in their tissues. The algae provide up to 98 percent of the corals' food. The corals provide protection and inorganic nutrients for the algae.

Some coral cells undergo meiosis. Which of these would not occur during meiosis?

A. formation of a zygote B. chromosomes crossing-over C. production of gametes D. reduction in number of chromosomes

Correct Answer: A

Which of these does not occur during meiosis?

A. production of identical gametes B. production of new gene combinations C. crossing-over of homologous chromosomes D. reduction of chromosome number by one-half

Correct Answer: A

Horses have 64 chromosomes in each body cell. If a horse cell undergoes meiosis, how many chromosomes should be in each gamete?

A. 16 B. 32 C. 64 D. 128

Correct Answer: B

What process produces male and female reproductive cells in plants?

A. mitosis B. meiosis C. replication D. fertilization

Correct Answer: B

Which of these combinations results in the expression of a recessive trait?

A. two dominant alleles B. a dominant sex-linked allele and a Y chromosome C. two recessive alleles D. a dominant allele and a recessive allele

Correct Answer: C