CST Test Questions

In certain breeds of dogs, deafness is due to a recessive allele (d) of a particular gene, and normal hearing is due to its dominant allele (D). What percentage of the offspring of a normal heterozygous (Dd) dog and a deaf dog (dd) would be expected to have normal hearing?

C) 50%

A student filled two Petri dishes with a clear cornstarch gel, then marked the letter "X" invisibly onto the gel in Petri dish 1 with a damp cotton swab. He then placed saliva from his mouth onto a second cotton swab and used that swab to mark the letter "X" invisibly onto the gel in Petri dish 2. Fifteen minues later, he rinsed both Petri dishes with a dilute solution of iodine to indiate the presence of starch. The surface of Petri dish 1 turned completely blue, indicating starch, except the letter "X" was clear, as shown above. The most probable explanation of the clear "X" is that ...

C) A chemical in the saliva broke down the starch in the gel

There are many different enzymes located in the cytoplasm of a single cell. how is a specific enzyme able to catalyze a specific reaction?

C) An enzyme binds to a specific substrate (reactant) for the reaction catalyzed

Which of these would have the least effect on natural selection in a subspecies of giraffes that is geogrphically isolated from other subspecies of giraffes?

C) Chromosome number

What causes tomatoes to ripen much more slowly in a refrigerator than they do if left ona table at room temperature?

C) Low temperatures reduce the action of ripening enzymes

Although there are a limited number of amino acids, many different types of proteins exist because the...

C) Sequence and number of amino acids is different

The table below list the typical diploid number of chromosomes of several different organisms. Which of the following is the best explanation for why the chromosome numberis an even number in each of these organisms?

C) The diploid chromosome number represents pairs of chromosomes, one from each parent, so it isalways an even number

5'A base sequence is shown below ACAGTGC How would the base sequence be coded on mRNA?

C) UGUCACG

If a paleontologist finds fossils of many different species existing in the same area at approximately the same time, the paleontologist can conclude that the ecosystem in this area had a high degree of ...

C) biological diversity

Earth has undergone some catastrophic changse from time to time. Which of these most likely explains why life on Earth continued following these catastrophes?

D) A wide diversity of species existed

Fur color in cats is controlled by an autosomal gene tht can occur in the dominate from (B), or the recessive form, (b). The length fo the cats fur is controlled by anoher autosomal gene that occurs in the dominant from (S), or the recessive from (s). The table below shows the traits for these allele codes. The following genotypes were found in a male cant and a female cat. BbSs (male) bbSS(female). Which one of the following choices is true of the phenotyple of offspring from these parents?

D) All offspring will have short-haired fur

How do human diseases caused by bacteria and diseases caused by viruses react to antibiotics?

D) Bacterial diseases respond to antibiotics; viral diseases do not

Which cellular organelle is responsible for packing the proteins that the cell secretes?

D) Golgi apparatus

In most stable freshwater environments, populations of Daphnia are almost entirely female and reproduce asexually. However, males are ovserved in low oxygen enviorments or when food is scarce. Based on these observations, a researcher suggests that male Daphnia develop in response to unfavorable environmental conditions. This is an example of a ...

D) Hypothesis

In fruit flies, the gene for red eyes (R) is dominant and the gene for sepia eyes (r) is recessive. What are the possible combinations of genes in the offspring of two red- eyed heterozygous flies (Rr)?

D) RR, Rr and rr only

Which of the following statemetns correctly describes meiosis?

D) The cells produced at the end of meiosis contain half the number of chromosomse as the parent cell

5' ATCAGCGCTGGC 3' The above sequence of DNA is part of a gene. How many amino acids are coded for by this segment?

A) 4

A food chain is shown below Grasses ---> Crickets ---> Field Mice ---> Hawks For the food chain shown, which of the following changes would have the most severe consequences?

A) A drastic decrease in rainfall, causing drought

Sweat and skin secretions contain a mixture of molecules that kills or limits the growths of many types of microbes. This control of microbes is an example of...

A) A nonspecific defense against infection

Which of thses best illustrates natural seletion?

A) An organism with favorable genetic variations will tend to survive and breed successfully

5' G T A _ _ _ A A 3' 3' C A T G C A T T 5' This segment of DNA has undergone a mutation in which three nucleotides have been deleted. A repair enzyme would replace them with ...

A) CGT

Which of these is best demonstrated by the experiment above?

A) Differentiated cells contain a complete set of genes

The diagram below shows Rosalind Ranklins x-ray diffraction image of DNA. How did this evidence affect the work of Watson and Crick?

A) It was used to determine the physical structure of DNA

The first stage of photosynthesis in a chloroplast is...

A) LIght-dependent

After a volcaniceruption has covered an area with lava, which of the following is the most likely order of succession in the repopulation of the area?

A) Lichens --> grasses -->shrubs --> trees

A computer model of cellular mitosis can simulate the aspects of cellular division quite well. However, microscopic observation of actual celluar mitosis can improve understanding because actual observations...

A) May reveal greater unknown complexities

If a corn plant has a genotyple of Ttyy, what are the possible genetic combinations that could be present in a single grain of pollen from this plant?

A) Ty, ty

One human disease is caused by a change in one codon in a gene from GAA to GUA. This disease is the result of...

A) a mutation

Some snake venoms are harmful because they contain enzymes that destory blood cells or tissues. The damae caused by such a snakebite could best be slowed by...

A) applying ice to the bite area

In carrier pigeons there is a rare inherited condition that causes the death of the chicks before hatching. In order for this disease to be passed from generation to generation there must be parent birds that...

A) are heterozygous for the disease

Individuals with HIV sometimes contract a pneumonia infection that is rare in the rest of the population because people with HIV...

A) are unable to fight off these pneumonia- causing organisms

The graph below shows the birth rate and death rate for a population during the 1900s. From 1900 to 2000, the populatin has...

A) increased

The diagram below shows a cellular process that occurs in organisms. This process is known as...

A) meiosis

Which of the following sequences represents chromosome number during fertillzation?

A) n+n-->2n

Mutations within a DNA sequence are...

A) natural proccesses that produce genetic diversity

Which of the following base pair sequences could be produced in DNA replication?

B) 5' AGTCAT 3' 3' TCAGTA 5'

Based only on the sex chromosomes in typical human egg and sperm cells at fertillization, the probability of producing a female is...

B) 50%

The bacterium Agrobacterium tumefaciens infects plants, and a portion of its DNA is inserted into the plants chromosoms. This causes the plant to produce gall cells, which manufacture amino acids that the bacterium uses as food. This process is a natural example of ...

B) Genetic manipulation

Which of the following best describes meiosis?

B) It occurs only in cells in the reproductive structures of the organism

A genetic disorder due to a recessive allele (a) is lethal in homozygous indiciduals (aa), whereas heterozygous individuals (Aa) have no symptoms. Based on this information, which of the following is likely to result?

B) The diorder will be maintained in the population through the reproduction of heterozygotes

Rabbits introduced into Australia over 100 years ago have have become a serious pest to farmers. Rabbit populations increased so much that they displaced many native sepecies of plant eaters. What is the most logical explanation for their increased numbers?

B) There are few effective predators

The plasma membrane of a cell consists of ...

B) Two layers of lipids organized with the nonpolar tails forming the interior of the membrane

A scientist puts nucleotide chians of UUUUUU in a test tube under conditions allowing protein synthesis. Soon the test tube is full of poypepride chians composed of only the amino acidphenylalanine. What does this experiment indicate?

B) UUU codes for the amino acid phenylalanine

The students were testing the amount of fertilizer that would best promote the growth of strawberriesin a garden. Which of the following could be an unavodable source of experimental error?

B) Variation in the strawberry plants

When the Mount St. Helens volcano erupted, the blast covered much of the surroundings area with ash. Based on the diagram above, which list shows the sequence of secondary succession that followed that eruption?

B) Z, X, Y, W

Carbon dioxide s produced as cells break down nutrients for energy. which of the following pairs of systems would participate in removing the carbon dioxide from the body?

B) circulatory and respiratory

The respiratory system depends on the nervous system for signals to...

B) coordinate muscles controlling breathing

A species of finch has been studied on one of the geographically isolated Galapagos Islans for many years. Since the island is small, the Lineage of every bird for several generations is konwn. This allows a family tree of each bird to be develped. some family groups have survived and others have died outl. The groups that survive probably have...

B) inherited some advantageous variations

A cell from heart muscle would probably have an unusually high proportion of...

B) mitochondria

A population of termites initially consists of darly colored and brightly colored members. After several generations, the termite population consists almost entirley of darly colored members becaue the brightly colored termites are easier or a predatory species of insectivores to locate. This situation is an example of...

B) natural selection

The cell membrane of the red blood cell will allow water, oxygen, carbon dioxide, and glucose to pass though. Because other substances are blocked from entering, this membrane is called...

B) semi-permeable

A signal that the bladder is full sent to the central nervous system by

B) sensory neurons

Which of the following is a fuction of the nervous system?

B) signaling muscle tissues to contract

Which of these would most likely cause a mutation?

B) the insertion of a nucleotide into DNA

Order of dominacne C--> cch-->ch-->c . The chart shows four alleles at the same locus that affect rabbits coat color. Each allele isdominant to the ones below it. Rabbits with an albino or Himalayan coat are more susceptible to predators. Which of the following genotypes will produce a rabbit that is least likely to survive?

C) c"c

The homoeostatic mechanism in humans that regulates blood pH depends on the feedback of information from..

C) chemical receptors

Which molecule is plant cells fist captures the radiant energy from sunlight?

C) chlorophyII

Fossil evidence suggests that a number of members of one fish speciesfrom an ancient lake in Death Valley, California, because several solated species. Each of these new species lived in a different pond. Which of the following best explains the cause of this speciation?

C) geographic isolation

Mendel hypothesized that reproductive cells have only one factor for each inherited trait. This hypothesis is supported by the observation that...

C) haploid cells are produced by meiosis

What is the greatest danger to a patient who has had damage to the skin?

C) infections in uncovered tissues

Genetic engineering has produced goats whose milk contains proteins that can be used as medicines. This effect was produced by...

C) inserting foreign genes into fertilized goat eggs

A healthy individual is a carrier of a lethal allele but is unaffected by it. what is the probable genotyple of this individual?

C) one recessive lethal allele and one dominant normal allele

The Sabin vaccine is a liquid containing weakened polio viruses. Vaccinated individuals become protected against polio because the weakend viruses...

C) promote production of anibodies

Striking the tendon just below the kneecap causes the lower leg to jerk. Moving an object quickly toward the face can cause the eyes to blind shut. These are examples of ...

C) reflex reaction

Which of these organisms would most likely be found at the top of an energy pyramid?

C) sharks

Injecting a person with a killed-bacteria vaccine can protect that individual from a disease because the proteins of the killed bacteria...

C) stimulate the production of antibodies which can be manufactured later in respnse to infection

Scientists found that, over a period of 200 years, a mountain pond was transformed into a meadow. During that time, several communities of organisms were replaced by different communities. Which of these best explains why new communities were able to replace older communities?

C) the abiotic characteristicsof the habitat changed

If a human baby boy inherits a reccessive allele from his mother, in which circumstance would he most likely show the trait coded for by the recessive allele?

C) the allele is on the X-chromosome

A single species of squirrel evolved over time into two species, each one opposite sides of the Grand Canyon. This change was most likely due to...

C) the isolation of the two groups

Which of these secretes a hormone that regulates the rate of metabolism of the body?

C) thyroid

In order for the body to maintain homeostasis, the chemical decomposition of food to produce energy must be followed by...

C) waste removal

In a pond, the primary producer is a green alga, Spirogyra; the primary consumer is the crustacean, Daphnia; the secondary consumer is a small fish, the bluegill; and the tertiary consumer is a larger fish, the smallmouth bass. What changes can be expected in the pondif the Daphnia are killed with pesticides?

D) The small mouth bass population will die

Which information was most important to the development of genetic engineering techniques?

D) The structure of DNA molecule

Which of the following best describes the use of population models in biology?

D) They can help predict outcomes

Which of the following require a host cell because they are not able to make proteins on their own?

D) Viruses

Which of these best completes this concept map?

D) a plant cell

The fight-or-flight response includes greater heart output and a rise in blood pressure. This response is due to...

D) adrenaline secreted by the adrenal glands

Complete buring of plant material returns carbon primarily to the ...

D) atmosphere

The clear protein of an egg white becomes opaque andfirm when cooked because the heat ...

D) changes the protein structure

The diagram above shows homologous chromosomes during prophase I of meiosis. Which of the following correctly describes the process being illustrated?

D) crossing-over in which alleles are exchanged

Maltose can be broken down into glucose molecules by the enzyme maltase. Which of the following would slow the reaction rate?

D) diluting with water

A base sequence is shown below. ACAGTGC How would the base sequence be coded on mRNA?

D) each half of the original DNA molecule is joined with a new complementary DNA strand

which of these organisms are most helpful in preventing Earth from being covered with the bodies of dead organisms?

D) fungi and bacteria

A small portion of a population that is geographically isolated from the rest of the population runs the rist of decreased....

D) genetic variation

Which of these organisms would most likely be found at the bottom of a biomass pyramid?

D) green algane

Eukaryotic cells are differentiated from prokaryotic cells because eukaryotic cells...

D) have nuclei

A small population of chimpanzees lives in a habitat that undergoes no changes for a long period. How will genetic drift probably affect this population?

D) it will reduce genetic diversity

According to this information, which group demonstrated the greatest biodiversity during the Cretaceous period?

D) lizards

A strand of mRNA containing the repeating sequence AAGAAGAAGAAG could code for which of the following amino acid sequences?

D) lys-lys-lys-lys

In aerobic respiration, the Kerbs cycle (citric acid cycle) takes place in...

D) mitochondria