LER 2023 Study Guide
less stable and less diverse
A Christmas tree farmer cuts down a native forest to plant Frasier fir trees. Compared to the original forest, the newly planted Christmas tree farm will most likely be _____________________________
the same genetic information, when compared to cells of the parent plant
A plant commonly referred to as "Mother of Thousands" has lost its ability to produce seeds. In order to reproduce, the edges of the plant's leaves asexually develop miniature plants that drop off and grow into mature plants. The cells of the offspring would have ____________________
a large number of identical offspring are produced
Bacteria reproduce asexually by a process known as binary fission. In binary fission, the bacterium's single chromosome is copied and the cell splits in half, with each new cell receiving a copy of the chromosome. The biggest advantage that binary fission often has over sexual reproduction is that _________________________
20°C
Base your answer to this question on the graph and on your knowledge of biology. The graph shows how the population growth rate of several species of fish is affected by temperature. What is the most favorable temperature for the growth of the yellow perch population?
altering the equilibrium of ocean ecosystems
Destruction of ocean habitats by pollution today means that the organisms living there may not survive in the future. By polluting the oceans, humans are ________________________________
increase reliability
During the Making Connections lab, several pulse readings are taken and averaged in order to ___________________________________-
twin A can synthesize a protein resulting in a particular trait and twin B cannot
Epigenetics The field of epigenetics is the study of changes in gene expression due to factors other than a change in the DNA sequence. One factor that can change gene expression is the attachment of a chemical, called a methyl group, to the DNA molecule. This attachment prevents that gene from being expressed, thereby altering that trait. Due to epigenetic effects, even identical twins may not be as identical as was once thought. The diagram below shows the DNA sequence of a gene present in a pair of identical twins. Twin B's gene shows an epigenetic effect. Based on the diagram, an explanation for why these identical twins are not identical in all traits is that _____________________________________________________
natural selection in H. pylori bacteria
Helicobacter pylori (H. pylori) is the bacterium responsible for most ulcers and many cases of stomach infl ammation. An antibiotic has been found to kill these bacteria. It works because H. pylori makes a particular enzyme that happens to react with the antibiotic and makes it poisonous to the bacterium. The sequences in the diagram below show the effects of antibiotic treatment on two strains of H. pylori, one of which does not produce the enzyme. The overall series of events best illustrates the process of ___________________________
additional food became available
One factor that could result in an increase in the population size after year 10 would be ____________
mutations and recombination
Some organisms have variations. Two sources of these variations are ________________________
Different parts of the genetic code may be used in each of the cell types.
Within a specific kind of tissue, there are different types of cells. In bone tissue, there are four different cell types, as shown in the picture. Since the four types of cells contain the same genetic instructions, how is it possible for them to have different shapes and carry out different functions?
sunlight
X most likely represents:
predator/prey
A graph of population changes of two animal species over time is shown. Using the information on the graph, what is the most likely relationship between these two populations?
the presence of these fluids in waterways could make them uninhabitable for aquatic organisms and reduce water supplies for humans
A major environmental concern in urban areas is pollution produced by automobiles. Fluids, such as oil and gasoline, may leak out of vehicles and end up in lakes, streams, and rivers. One reason why scientists are concerned about this type of pollution is that _______________________________
the nonnative species has no natural enemies present in the ecosystem
A native species is competing for resources with a nonnative species that was accidentally introduced into the area. The nonnative species is more likely to survive than the native species when ______________________
an increase in carbon dioxide in her blood
A student was jumping rope and noticed that her heart was beating faster. The student's heart rate probably increased as a result of _________________________
The shops, bars, and restaurants agreed to close early, even though they could lose customers, so that the turtles could have a better chance to nest successfully.
A trade-off was made by the local population that has increased the number of turtles in the area. Which statement best describes the trade-off?
the stomach may have a more suitable environment for the enzyme to work
An enzyme that rapidly breaks down a protein molecule in the stomach may break down that same protein much more slowly in the small intestine or mouth because ___________________________________________
much of the energy at each level is lost as heat
Base your answer this question on the information and diagram shown and on your knowledge of biology. The diagram represents the energy relationships in a forest ecosystem. The best explanation for the decrease in the amount of energy available as one moves up the pyramid is that _________________________________________-
conduct their own experiments to see if they arrive at the same conclusion
Colombia is a country in South America that grows and exports a large portion of the coffee that is used by Americans. A group of scientists in Colombia conducted an experiment on the effects of coffee on the development of Alzheimer's disease in elderly people. Their conclusion was that drinking coffee every day will decrease the occurrence of Alzheimer's disease, and they recommended that Americans drink coffee several times a day. In order to evaluate this conclusion and before they encourage Americans to drink more coffee, scientists in the United States should ________________________________________________
black, due to having the same DNA as the donor cat
Copy Cat In February 2002, Cc — the fi rst-ever cloned cat — was introduced to the public by researchers at Texas A&M University. The kitten had been born December 22, 2001, but announcement of the successful cloning was delayed until the animal had completed its shot series and its immune system was fully developed. In the cloning process, DNA [the nucleus] was transplanted from the 2-year-old donor mother cat into an egg cell whose nucleus had been removed. This embryo then was implanted into the surrogate mother cat. ... If a donor cat was black and the surrogate mother was white, then the cloned cat would likely be _____________________________________________
If the egg cell nucleus remains in the cell, then there will be three copies of all cat chromosomes in the cloned cat
Copy Cat In February 2002, Cc — the fi rst-ever cloned cat — was introduced to the public by researchers at Texas A&M University. The kitten had been born December 22, 2001, but announcement of the successful cloning was delayed until the animal had completed its shot series and its immune system was fully developed. In the cloning process, DNA [the nucleus] was transplanted from the 2-year-old donor mother cat into an egg cell whose nucleus had been removed. This embryo then was implanted into the surrogate mother cat. ... Which statement represents an explanation for why it is necessary to remove the nucleus from the egg cell used during the cloning process?
32%
DNA is formed using four kinds of base subunits. In a double-stranded segment of DNA, the percentage of the base C is 18%. What is the approximate percentage of base T?
electrical charge and size
DNA samples were taken from four different species of animals labeled A, B, C, and D. The diagram below represents the results of a procedure that separated the DNA fragments from each species. The fragments of DNA separated into these bands because of their __________________________________
A
DNA samples were taken from four different species of animals labeled A, B, C, and D. The diagram below represents the results of a procedure that separated the DNA fragments from each species. The species that has the band containing the smallest DNA fragment for the sample that was sequenced is ____________________________________
egg cells
Each of the cells present in a woman contains a complete set of chromosomes. The only exceptions are her __________________________________
can be infl uenced by environmental factors
Epigenetics The field of epigenetics is the study of changes in gene expression due to factors other than a change in the DNA sequence. One factor that can change gene expression is the attachment of a chemical, called a methyl group, to the DNA molecule. This attachment prevents that gene from being expressed, thereby altering that trait. Due to epigenetic effects, even identical twins may not be as identical as was once thought. The diagram below shows the DNA sequence of a gene present in a pair of identical twins. Twin B's gene shows an epigenetic effect. Researchers have shown that environmental factors, such as exposure to toxins, can bring about epigenetic effects. This research suggests that an organism's traits ___________________________________________
the amount of energy available to the biosphere was decreased
Evidence suggests that a large meteorite hit Earth 65 million years ago, causing a layer of dust to block the Sun, cooling the planet. It is estimated that 70% of all plant and animal species, including the dinosaurs, died off as a result. The best explanation for the deaths of these organisms is that ______________________
scientifi c understandings can change as new information becomes available
For years, scientists believed that flight evolved when ancestral birds climbed trees and then glided back to the ground. Recent fossil evidence suggests that flight may have evolved from the ground up, as early birds used to jump off the ground as a way to avoid predators. These discoveries suggest that __________________________________________
increasing our reliance on energy sources such as fossil fuels
Human society has become increasingly dependent on industry and technology. While this has had many benefits, it also has had the disadvantage of _____________________________________
when humans alter ecosystems by adding specifi c organisms, serious consequences can result
Hydrilla, a plant native to Central Africa, was widely used in home aquaria. Hydrilla was often dumped with aquarium water into drains, sewers, or ponds. It then thrived and has become an invasive species, disrupting aquatic ecosystems from Florida through the northeast United States. Removing Hydrilla from these ecosystems will most likely require either physically removing it or adding chemicals to the affected waters to kill it. The result of the introduction of Hydrilla into native ecosystems in the United States has shown that ___________________________________
similar, because water molecules will still move across the membrane in a similar manner
If a 1% salt solution were substituted for the starch solution in this setup, the results would be __________________________________
cause the immune system to produce special proteins that will recognize and destroy the virus
In order to prepare for a future outbreak of Ebola, a harmful virus, two vaccines were tested. In order for either of these vaccines to be effective, they must _____________________________________
could remain in the clothing or bedding and harm humans later
Infestation with bedbugs is a serious health problem, and scientists seeking to control bedbug reproduction are constantly researching new options. It has now been shown that freezing any articles of clothing or bedding containing bedbugs at a temperature below -15°C for 3.5 days will kill all of the bedbugs and their eggs. Using the technique of freezing is preferable to using chemical insecticides because a major disadvantage of using chemical pesticides is that they _____________________________
dynamic equilibrium
One result of the ability of organisms to detect and appropriately respond to stimuli is _____________________
Pond A has greater biodiversity than pond B because there are more species present.
Students were studying the different species of organisms in two different pond ecosystems. Their fi ndings are summarized in the chart below. Species Present in Two Pond Ecosystems Plant Species Microorganism Species Pond A 10 20 Pond B 11 5 Based on the information in the chart, how does the biodiversity present in pond A compare to the biodiversity present in pond B?
may be used to produce chemicals that can be used to treat certain human disorders
The diagram below represents part of a biological process that begins with a chromosome containing a specific human gene being removed from a human cell. The overall process is important because it _____________________________________
both day and night, because respiration is occurring all the time in plants and animals
The graph shows changes in dissolved oxygen in a pond in the summertime over a 24-hour period. A large population of fi sh was introduced into the pond. During which part of the day would these fi sh affect the dissolved oxygen level in the pond?
Photosynthesis produces more oxygen during the day than is used by respiration.
The graph shows changes in dissolved oxygen in a pond in the summertime over a 24-hour period. What is the most likely reason for the variation in the dissolved oxygen levels in the pond over the 24-hour period?
The spring peeper population is at about the same level in 2007 as it was in 1995.
The graphs display the percent of monitoring stations where three different amphibian species were seen. The data were collected between 1995 to 2007 in the wetlands surrounding the Great Lakes. Which claim is best supported by the data represented in the graphs?
dinosaurs and birds share a common ancestor
The illustrations below are of an organism called Archeopteryx, which lived approximately 150 million years ago. Archeopteryx had teeth and claws like a dinosaur and wings with feathers like a bird. Such fossils allow scientists to conclude that ____________________________________
No, because this structural evidence alone is insuffi cient and molecular evidence should be obtained.
The illustrations represent cross sections of two different plant stems. A student compared two stem cross sections. Stem cross section A is from a plant that can be used to produce products with valuable medicinal properties. Stem cross section B is from a plant growing in the same area of the forest and its usefulness for producing medicines is unknown. The student concluded that the stem cross sections had many structural similarities and that the plant that produced cross section B would produce the same valuable medicinal products.
burning fossil fuels
The population of reindeer has been decreasing over the last 20 years in the Arctic because climate change has led to more rainfall there. The rain freezes on top of the snow, preventing the reindeer from getting through the snow to fi nd food. Which action by humans has most likely contributed to climate change?
changed in size due to environmental changes that affected the survival of different-sized snails
The series of fossil snail shells below represents 10 samples that were collected from deposits laid down from 10 million years ago to 3 million years ago. The shells are arranged in order by age. The shells shown represent how they looked at various times over a 7-million-year period. It would be most accurate to conclude that the snails of this species _______________________________
the tongue variation provides the species with an advantage in surviving and reproducing
The tube-lipped nectar bat, found in Madidi National Park in Ecuador, has the longest tongue in relation to its size of any mammal. Its 8.5 cm tongue can reach into the deepest flowers. It is likely that the population of these bats with exceptionally long tongues will increase in the Madidi National Park ecosystem if ______________
The uterus is where the fetus develops internally until birth.
What is true about the functioning of the human reproductive system?
a feedback mechanism
When a person is threatened, the pituitary gland releases a hormone that stimulates the adrenal glands to release stress hormones. These stress hormones can cause a temporary increase in heart rate. This is an example of
an allergic reaction
When a person receives a transplanted organ, many medications are necessary to keep the organ from being rejected. The process of organ rejection is similar to the one involved in ______________________________
maintain homeostasis by reducing the evaporation of water
When a plant is in a hot and dry environment, the guard cells may close the stomate openings in the leaves. This action will directly ____________________________
meiosis, fertilization, mitosis, differentiation
Which row in the chart contains the correct sequence of events involved in the formation of a human embryo?
ATP
the removal of mitochondria from a typical animal cell would have an immediate effect on the cell's production of _____________________
acidity of the water
what factor would be an abiotic limiting factor for fish living in a lake in New York State?