BIOLOGY REGENTS

Mad cow disease is a fatal disease that destroys brain tissue. Researchers have found that a prion protein, which is an abnormally constructed molecule, is responsible. Which statement best describes the characteristics a protein must have to function correctly? (1) A protein is a long chain of amino acids folded into a specific shape. (2) A protein is a long chain of simple sugars folded into a specific shape. (3) A protein is made of amino acids synthesized into a short, circular chain. (4) A protein is made of simple sugars synthe- sized into a short, circular chain.

1. A protein is a long chain of amino acids folded into a specific shape

Many biotic factors affect individuals in a population. An example of an organism being directly affected by a biotic factor is (1) a squirrel cannot find a mate (2) a flood washes away a maple tree (3) a plant is in a dark room (4) a chipmunk finds a rock pile to use for a home

1. A squirrel cannot find a mate

Before a new shopping center can be built on previously undeveloped land, the builders must submit a proposal to the local government for approval. Which statement identifies an environmental concern associated with the development of the shopping center? (1) Building the center would decrease resources needed by local organisms. (2) The new shopping center would increase competition with already existing businesses. (3) Building the center would decrease the amount of pollution in the area. (4) The new shopping center would increase the biodiversity of the area.

1. Building the center would decrease resources needed by local organisms

A student wondered if butterflies would show any differences in their wing color if, as caterpillars, they were grown in the dark or grown in bright white light. Which statement would be a possible hypothesis for an experiment to test this idea? (1) Caterpillars exposed to bright white light will show more blue and green in their wings when they become butterflies than caterpillars kept in the dark. (2) Will caterpillars kept in the dark have brighter wings when they become butterflies than caterpillars exposed to bright white light? (3) Ten caterpillars will be kept in the dark and ten caterpillars will be exposed to bright white light and allowed to develop into butterflies. (4) Results show that caterpillars kept in the dark and those exposed to bright white light had the same wing color when they became butterflies.

1. Caterpillars exposed to bright white light will show more blue and green in their wings when they become butterflies than caterpillars kept in the dark

Many oak trees are cut down and removed from an oak-hickory forest. A likely result of the direct harvesting of the oak species would be the (1) disruption of natural cycles (2) conservation of these natural forest resources (3) recycling of all the nutrients in the forest (4) prevention of the extinction of animals native to the area

1. disruption of natural cycles

After feeding at the surface of the ocean during the day, many ocean organisms migrate to deeper waters. While there, they release ammonia in their urine. Many bacteria use the nitrogen from the ammonia as they make amino acids, which eventually end up in food chains on both land and water. These amino acids may even be used in humans. Which statement best explains these observations? (1) Chemical elements, including nitrogen, pass through food webs and are combined and recombined in different ways. (2) Chemical elements, including nitrogen, are removed from food webs and eliminated from ecosystems. (3) Nitrogen is transferred directly from bacteria to humans. (4) All elements in the ocean remain there and are not transferred to other ecosystems.

1. Chemical elements, including nitrogen, pass through food webs and are combined and recombined in different ways.

Humans have an effect on ecosystems when they use native grasslands or forested areas for farming or urban use. One negative effect of these changes on the ecosystem is that there will be (1) Less biodiversity (2) More homes (3) Successful economic growth (4) Increased food production

1. Less biodiversity

The reproductive structure in a female mammal that produces sex cells is the (1) ovary (2) testes (3) uterus (4) placenta

1. Ovary

A child with cystic fibrosis has an altered protein in his cells that stops chloride ions from leaving the cells. This protein most likely affects the functioning of (1) cell membranes (2) nuclei (3) mitochondria (4) ribosomes

1. cell membranes

Scientists who study rock formations in caves describe some of the formations as "living rock" because, under certain conditions, they increase in size. Which statement would best dispute the claim that these rock formations are living? (1) Rocks are not composed of cells, while living organisms are. (2) Rocks perform complex metabolic processes, but cannot grow. (3) Rocks cannot reproduce sexually. (4) Rocks remain stable in a wide range of physical conditions.

1. Rocks are not composed of cells, while living organisms are

The following events occur during sexual reproduction: A. mitosis B. meiosis C. fertilization D. birth Which sequence represents the correct order of these events during sexual reproduction? (1) A→C→B→D (2) B→C→A→D (3) C→B→A→D (4) B→A→C→D

2. (2) B→C→A→D

Which change is an example of a response to a stimulus? (1) The pupil of an eye decreases in size in bright light. (2) A leaf absorbs sunlight in the morning (3) The water level of a pond rises on a rainy day. (4) A dead tree decays after many years.

1. The pupil of an eye decreases in size in bright light

Proteins, starch, and DNA are similar in that they are all (1) organic compounds (2) parts of genes (3) made of amino acids (4) made of simple sugars

1. organic compounds

Carbon dioxide and oxygen are important resources in ecosystems and are (1) recycled through the activity of living and nonliving systems (2) stored in the animals of the ecosystem (3) lost due to the activities of decomposers (4) released by the process of photosynthesis

1. recycled through the activity of living and nonliving systems

A shark and a dolphin have similarly shaped bodies and fins. However, these two organisms are not closely related: The shark is a fish, and the dolphin is a mammal. Some species may have similar body structures even if they are not related because they evolved in (1) similar environments and specific traits increased their chances of survival (2) similar environments and were exposed to factors that caused exactly the same mutations (3) different environments, but tried to adapt in the same ways so they could survive (4) different environments, but ate similar foods that affected their growth and development

1. similar environments and specific traits increased their chances of survival

Natural selection produces changes most quickly in (1) species with short reproductive cycles (2) individual pathogens killed by antibiotics (3) complex multicellular organisms (4) individuals that produce a small number of offspring

1. species with short reproductive cycles

When people receive organ transplants, they often need to take medications that decrease immune responses because (1) transplanted organs contain antigens that can trigger white blood cell activity (2) hormones present in replacement organs prevent the synthesis of antibiotics (3) transplanted organs produce their own antibiotics (4) antigens present in these organs attack antibodies already present in the blood

1. transplanted organs contain antigens that can trigger white blood cell activity

A Chihuahua is born having a trait that is different from either of its parents. A possible explanation for the difference is that the Chihuahua puppy (1) was produced as a result of the recombination of genes during sexual reproduction (2) was produced as a result of the process of asexual reproduction (3) inherited a gene from one of its grandparents and not its parents (4) had a mutation that occurred after it was born

1. was produced as a result of the recombination of genes during sexual reproduction

Scientists have studied oceanic plastic garbage "patches" around the world. These are areas that accumulate plastic garbage from coastal regions. Their environmental effect ranges from killing sea life to blocking sunlight from reaching photosynthetic organisms. Without a change in human plastic usage, new garbage patches will continue to form. Which human activity would most directly reduce the amount of plastic garbage that enters the ocean? (1) Ban the production and usage of all bags made from recycled plastic. (2) Clean up plastic trash from shorelines, rivers, and other waterways that flow into the oceans. (3) Manufacture fewer reusable water bottles, so that people will be more likely to use disposable ones. (4) Implement a glass bottle deposit system to discourage people from recycling plastic bottles.

2. Clean up plastic trash from shorelines, rivers, and other waterways that flow into the oceans

It is recommended that people avoid excessive use of tanning beds. Exposure to the radiation emitted by tanning beds can cause skin cancer. This cancer is the direct result of a (1) change in a starch molecule (2) mutation in the genetic material (3) mutation in a protein (4) change in a fat molecule

2. Mutation in the genetic material

Which organisms and set of characteristics are correctly paired? (1) Fungi-carry out photosynthesis and heterotrophic nutrition (2) Plants-carry out respiration and autotrophic nutrition (3) Decomposers-carry out photosynthesis and autotrophic nutrition (4) Animals-carry out autotrophic nutrition and heterotrophic nutrition

2. Plants-carry out respiration and autotrophic nutrition

Which statement is an example of how the external environment can influence gene expression? (1) Some flowering plants that inherit a gene for white flowers and a gene for red flowers will produce pink flowers. (2) Some animals that inherit genes for brown fur will grow white fur if the outside temperature falls below a certain level. (3) In some breeds of cat, certain fur-color genes are found only in females. (4) A pea plant is short-stemmed only if it inherits the genes for the trait from both parents.

2. Some animals that inherit genes for brown fur will grow white fur if the outside temperature falls below a certain level

A chemical was added to hand sanitizers and dish detergents to kill bacteria. Certain species of bacteria are no longer killed by this chemical. One likely reason for the decreased effectiveness of this chemical is that these bacteria have (1) slower metabolic rates (2) a mutation for resistance (3) been selectively bred for survival (4) an adaptation to a different niche

2. a mutation for resistance

The burning of fossil fuels has harmed the environment by (1) decreasing acid rain in the northeast United States (2) adding carbon dioxide to the atmosphere (3) increasing biodiversity in the lakes and ponds of the Adirondacks (4) depleting the ozone shield directly over western New York State

2. adding carbon dioxide to the atmosphere

One characteristic of a stable ecosystem is (1) a high number of predators (2) an interdependence of organisms (3) a lack of biodiversity (4) an increase in human interference

2. an interdependence of organisms

Scientists have developed the ability to manufacture hormones, such as human growth hormone, using bacteria. One benefit of this new technology is that (1) scientists can use only one type of bacteria (2) bacteria are relatively inexpensive and reproduce quickly (3) patients can spend more money on their medications (4) scientists produce drugs that cause more immune reactions

2. bacteria are relatively inexpensive and reproduce quickly

Fungi are decomposers that play an important role in the maintenance of an ecosystem. The role of fungi is important because they (1) synthesize energy-rich compounds that are directly used by producers (2) break down materials that can then be used by other organisms (3) limit the number of plants that can perform photosynthesis in an area (4) are competitors of other consumers such as herbivores

2. break down materials that can then be used by other organisms

The kidney is an organ that collects wastes and excess water from the blood and sends them to the bladder where they are stored before being removed from the body. Which two systems work together to perform this function? (1) immune and respiratory (2) circulatory and excretory (3) skeletal and nervous (4) digestive and circulatory

2. circulatory and excretory

According to scientists, ocean waves could be a source of energy. Devices are being designed to capture the energy from waves and supply electricity to coastal areas. A direct benefit of utilizing this technology to produce energy would be the (1) destruction of habitats near the devices (2) decreased use of nonrenewable resources (3) release of gases needed for photosynthesis (4) increased use of finite resources

2. decreased use of nonrenewable resources

Finches on the Galapagos Islands express a variety of traits. Variability in the offspring of these finches is a result of (1) mutation and cloning (2) meiosis and mutation (3) mitosis and asexual reproduction (4) mitosis and genetic recombination

2. meiosis and mutation

The processes of diffusion and active transport are both used to (1) break down molecules to release energy (2) move molecules into or out of cells of the body (3) bring molecules into cells when they are more concentrated outside of the cell (4) move molecules against a concentration gradient, using ATP molecules

2. move molecules into or out of cells of the body

Homeowners have been encouraged to learn how to identify invasive plants and to remove them if they find them. The most likely reason for removing invasive plants is to (1) allow only one type of native plant to grow (2) preserve biodiversity (3) eliminate unfamiliar food sources (4) increase the rate of ecological succession

2. preserve biodiversity

In response to an increasing blood glucose level, the human body will normally (1) store the glucose in cell nuclei (2) release a hormone that lowers the blood glucose (3) produce a hormone that destroys the glucose (4) use the excess glucose to make proteins

2. release a hormone that lowers the blood glucose

Which life function is not necessary for an individual organism to stay alive? (1) nutrition (2) reproduction (3) regulation (4) excretion

2. reproduction

A fruit fly is classified as a consumer rather than as a producer because it is unable to (1) reproduce asexually (2) synthesize its own food (3) release energy stored in organic molecules (4) remove wastes from its body

2. synthesize its own food

Which cellular change in an organism could be inherited by the next generation? (1) a change in the ribosomes in the pancreas of a squirrel (2) the deletion of a single DNA base in a sperm cell of a trout (3) a decrease in the size of a vacuole in a rose leaf cell (4) the transfer of a piece of a chromosome in the skin cell of a raccoon

2. the deletion of a single DNA base in a sperm cell of a trout

Although all of the cells of a plant contain the same genetic material, root cells and leaf cells are not identical because they (1) use different genetic bases for the synthesis of DNA (2) use different parts of their genetic instructions (3) select different cells to express (4) delete different sections of their enzymes

2. use different parts of their genetic instructions

Organisms contain compounds such as proteins, starches, and fats. The chemical bonds in these compounds can be a source of (1) amino acids (2) simple sugars (3) energy (4) enzymes

3. Energy

Which structures regulate water loss and gas exchange in the leaves of plants? (1) vacuoles (2) chloroplasts (3) guard cells (4) mitochondria

3. Guard cells

Which change is an example of maintaining dynamic equilibrium? (1) A plant wilts when more water is lost from the leaves than is lost by the roots. (2) A plant turns yellow when light levels are very low. (3) Insulin is released when glucose levels in the blood are high. (4) A person sweats when the environmental temperature is low.

3. Insulin is released when glucose levels in the blood are high

Some states require shoppers to pay a deposit on certain beverage containers made of plastic and glass. When shoppers return the containers, their deposits are returned to them. How is this system intended to help the environment? (1) It encourages people to buy products that do not have a deposit. (2) It reduces the amount of money shoppers actually spend. (3) It reduces the amount of plastics and glass put into landfills. (4) It forces manufacturers to reduce air pollu- tion when they are making the containers

3. It reduces the amount of plastics and glass put into landfills

Increased concern over the number of heat- related illnesses among football players has led to a possible change in uniform design. Shoulder pads were designed that constantly blew cool, dry air underneath the shoulder pads. Tests showed that the use of the device during rest and recovery periods resulted in a reduction of body temperature and heart rate. This new device would help the athlete to (1) control the rate of muscle activity (2) increase muscle strength (3) maintain homeostasis (4) eliminate the release of heat from the body

3. Maintain homeostasis

Which statement best describes what is most likely to occur if an animal population grows larger than the carrying capacity of its environment? (1) The birth rate will increase. (2) Both the birth rate and death rate will decrease. (3) The death rate will increase. (4) Neither the birth rate nor the death rate will decrease

3. The death rate will increase

A broad body of evidence, subject to revisions, supported by different kinds of scientific investi- gations and often involving the contributions of scientists from different disciplines is necessary to develop (1) an inference (2) a fact (3) a theory (4) a prediction

3. a theory

Scientists are developing a malaria vaccine that would most likely contain (1) weakened drugs used to treat the symptoms of malaria (2) white blood cells from the malaria-infected individuals (3) a weakened form of the malaria-causing organism (4) antibodies made from the malaria-causing organism

3. a weakened form of the malaria-causing organism

Which activity would eventually result in a stable ecosystem? (1) deforestation in an area to increase space for the species living there (2) mowing a large field so it can be used for recreation (3) allowing native plants to grow undisturbed in an abandoned field (4) spraying pesticides on a field at the end of each growing season

3. allowing native plants to grow undisturbed in an abandoned field

Within the fish population, variations exist in color, size, gamete production, and swimming speed. A variation that would most likely be passed on to future generations of the species is (1) a swimming speed that is less than that of its predators (2) the presence of bright, colorful markings that contrast with the lake bottom (3) being of a size that enables them to hide among the rocks in the lake (4) the production of a small number of gametes during the peak of the breeding season

3. being of a size that enables them to hide among the rocks in the lake

Microbeads are tiny, smooth, plastic spheres found in common household products such as facial soap. These beads, measuring from 0.0004 to 1.24 mm, roughly the size of some fish eggs, are too small to be removed by water treatment systems. Thus, they end up in rivers, lakes, and other bodies of water. The accumulation of these microbeads is an environmental concern for aquatic biologists because microbeads (1) make the lakes and rivers cloudy and dirty, affecting their appearance (2) may stick to some household water pipes, preventing drainage problems (3) could be mistaken for food by some species, working their way up the food chain (4) could clog fishing nets, affecting the ability of fishermen to catch fish

3. could be mistaken for food by some species, working their way up the food chain

For centuries, humans have used resources from coastal areas and open ocean waters. An example of an activity that would promote the conservation of coastal areas and ocean resources is (1) harvesting large numbers of different fish species (2) allowing all-terrain vehicles access to beach areas (3) creating protected zones of natural grasses and shrubs in beach areas (4) encouraging the construction of factories along the ocean shoreline

3. creating protected zones of natural grasses and shrubs in beach areas

Scientists have recently discovered a community of bacteria and clams living under an ice shelf in Antarctica. These organisms live under 600 feet of ice, in the absence of sunlight, and in temperatures considered too cold for most living organisms. The location where these organisms live is unusual because (1) only biotic factors control the size of the populations (2) bacteria and clams are found in the same area (3) of the abiotic factors found in their environment (4) green plants make energy-rich compounds available

3. of the abiotic factors found in their environment

Which dissolved substance do aquatic animals remove from their external environment for use in cellular respiration? (1) carbon dioxide (2) ATP molecules (3) oxygen molecules (4) nitrogen gas

3. oxygen molecules

Botulinum toxin is a substance that can cause paralysis in humans. The effects of the toxin are due to the blocking of a signaling molecule that is necessary for communication between nerve cells. The toxin most likely interferes with the normal functioning of a (1) chromosome (2) DNA molecule (3) receptor (4) digestive hormone

3. receptor

The sequence that best illustrates the flow of energy through an ecosystem is (1) sunlight → plant → wolf → rabbit (2) plant → sunlight → rabbit → wolf (3) sunlight → plant → rabbit → wolf (4) wolf → rabbit → plant → sunlight

3. sunlight → plant → rabbit → wolf

Scientists have studied the return of plant life on Mount St. Helens ever since the volcano erupted in 1980. Wildflowers began colonizing the area, followed by shrubs and small trees. Scientists predict that it will likely take hundreds of years before the area returns to a forest dominated by fir and hemlock trees. These changes are an example of (1) humans degrading an ecosystem by remov- ing wildflowers (2) the loss of genetic variation in a plant species (3) the growth of a forest through ecological succession (4)the biological evolution of wildflowers, shrubs, and trees

3. the growth of a forest through ecological succession

Eye color, hair color, and skin color often vary from person to person and even within a family. One explanation is that (1) the glucose units in a DNA molecule are often rearranged (2) the genetic material of the female parent has the most influence on offspring (3) the inherited traits of individuals are determined by different gene combinations (4) some extra parts of genetic material are often gained during fertilization

3. the inherited traits of individuals are determined by different gene combinations

Traditional lightbulbs are only 10% efficient. Ninety percent of the energy they use is converted to heat. Modern lightbulbs are much more efficient, but may cost three times as much as traditional lightbulbs. Consumers who switch to modern lightbulbs are most likely (1) spending more money for no good reason (2) trying to stop pollution of the oceans (3) trading a short-term cost for long-term savings (4) helping traditional lightbulb factories employ people

3. trading a short-term cost for long-term savings

An example of recycling is (1) using a paper cup instead of a mug (2) turning off the lights when leaving a room (3) using plastic from a soda bottle to make a certain type of clothing (4) using two paper towels rather than five to clean up a spill

3. using plastic from a soda bottle to make a certain type of clothing

Which statement describes an event that would most severely disrupt the process of ecological succession in an area? (1) The season changes from spring into summer. (2) Native plants are planted in an abandoned field. (3) Plants and animals begin to colonize a newly formed volcanic island. (4) A dam is built on a river to form a reservoir.

4. A dam is built on a river to form a reservoir

Which statement is an accurate description of genes? (1) Proteins are made of genes and code for DNA. (2) Genes are made of proteins that code for nitrogen bases. (3) DNA is made of carbohydrates that code for genes. (4) Genes are made of DNA and code for proteins.

4. Genes are made of DNA and code for proteins

Several companies now offer DNA "banking services," where DNA is extracted from a pet and is stored so that a "replacement pet" might be produced using cloning techniques when the original pet dies. Which statement best explains why the replacement pets that are produced in this way might not look or act like the original? (1) The new animal must get the DNA from two different parents, not just one cell. (2) Mutations could occur that change the cloned animal into a completely different species. (3) Recombination of the cells as they are cloned will make the resulting pet act differently. (4) The environment could influence how genes are expressed, changing how the animal looks and acts.

4. The environment could influence how genes are expressed, changing how the animal looks and acts

A student performed an experiment to see if water temperature affects the level of activity in aquatic snails. The student set up four tanks with five snails in each tank. All four of the setups were identical in every way, except for the temperature of the water. In order to make the conclusions more valid, the student could (1) alter the pH of the water (2) change the size of the tank (3) carry out the experiment for a shorter period of time (4) use a larger number of snails

4. use a large number of snails

Which method of collecting data would provide the most accurate information about how an ecosystem is being affected by human development? (1) The people in the neighborhood record the number of birds they see in the area both before and after the construction of a new building. (2) Deer in the area are identified before construction so that scientists can see where they go after the building is finished. (3) More trees are planted in the area around the construction site to allow the animals a new place to live. (4) The population size is recorded for each species present in the construction area before and after the building is completed

4. The population size is recorded for each species present in the construction area before and after the building is completed

As a result of habitat destruction, the size of the Florida panther population has been drastically reduced. It is estimated that there are only 100 to 160 Florida panthers in the wild. Which statement best explains why the Florida panther population may not continue to evolve? (1) There is no longer a chance of mutations occurring in the population. (2) There is a lack of competition for limited environmental resources. (3) There is no longer a chance of a trait providing a reproductive advantage to the population. (4) There is a lack of genetic variation for selection to act upon.

4. There is a lack of genetic variation for selection to act upon

One of the best ways to represent the interdependence of all of the organisms in this ecosystem is (1) an evolutionary tree (2) a food chain (3) an electrophoresis gel (4) a food web

4. a food web

Before they can pass from a parent cell to its offspring cells, the inherited instructions that a human cell carries must first be (1) moved into the nucleus (2) broken down and made into DNA molecules (3) used to make specific protein molecules that form genes (4) accurately replicated

4. accurately replicated

The emerald ash borer is an insect that is thought to have been accidentally brought to the United States from China in shipping containers. It attacks ash trees, eventually killing the trees, destroying an important part of the ecosystem. The presence of the emerald ash borer in the United States can be used as an example of how humans have (1) purposely introduced an insect to correct a problem in an ecosystem (2) used an insect to remove one insect species and replace it with another (3) worked to increase the biodiversity in a particular area (4) altered the equilibrium in an ecosystem by introducing a new species

4. altered the equilibrium in an ecosystem by introducing a new species

Energy drinks have become increasingly popular. Some of these drinks contain large amounts of caffeine, which is known to increase heart rates in most individuals. This effect on the heart rate can be dangerous because it can lead to (1) a disruption in the absorption of starch (2) an increase in blood volume (3) a decrease in oxygen levels (4) an imbalance in homeostasis

4. an imbalance in homeostasis

The most likely result of completely removing carbon dioxide from the environment of a plant is that sugar production will (1) continue at the same rate (2) increase and oxygen production will also in- crease (3) increase and oxygen production will stay the same (4) decrease and eventually stop

4. decrease and eventually stop

The hemlock wooly adelgid is an invasive insect species that is destroying native hemlock trees in New York State. These insects can upset natural ecosystems because they (1) provide food for native bird species (2) can carry diseases that can be spread to pets (3) increase biodiversity in New York State forests (4) disrupt habitats that native species depend upon

4. disrupt habitats that native species depend upon

Phosphorus is necessary for the growth of healthy plants. Scientists are developing plants that can grow in phosphorus-poor soil. Some of these new varieties, produced in a lab, make extra copies of a protein that helps them obtain more phosphorus from the soil. The process being used to develop these new varieties is most likely (1) paper chromatography (2) natural selection (3) direct harvesting (4) genetic engineering

4. genetic engineering

Monarch butterflies migrate from the U.S. and Canada to Mexico every winter. Over the past 10 years, there has been a drastic decrease in the number of monarch butterflies. Scientists have estimated that the population may have decreased from about 1 billion to 35 million. Which action would not be considered a reason for the decline in monarch butterfly populations? (1) illegal deforestation (2) extreme temperature changes (3) decreasing food supplies (4) habitat preservation

4. habitat preservation

In 2011 and 2012, scientists working on the Banana River in Florida recorded a dramatic increase in the number of manatee deaths. Over the past 50 years, this area has also seen the human population increase by more than 500,000 people. It is believed that pollution from numerous sewage tanks leaked into the water, eliminating the manatees' food source, replacing it with an alga that is toxic to the manatee. This is an example of (1) a natural cycle in an ecosystem (2) the effect of increased biodiversity on an ecosystem (3) direct harvesting in an ecosystem (4) human actions altering ecosystems with serious consequences

4. human actions altering ecosystems with serious consequences

When rain forests are cut down, there is a (1) loss of fossil fuels that could be used by industry (2) release of excess oxygen to the atmosphere (3) release of chemicals which cause helpful mutations (4) loss of genetic material available for research

4. loss of genetic material available for research

Organic compounds are used as building blocks for (1) water, DNA, and starches (2) water, proteins, and oxygen (3) proteins, DNA, and carbon dioxide (4) proteins, starches, and fats

4. proteins, starches, and fats

Exposure to certain environmental toxins, such as pesticides, may reduce fertility in males by interfering with their ability to produce gametes. These toxins are most likely having an effect on the (1) testes and progesterone (2) ovaries and testosterone (3) ovaries and estrogen (4) testes and testosterone

4. testes and testosterone

Scientists recently discovered that three different types of squid, a marine animal, previously thought to be three different species, were actually all members of one species. Their earlier ideas were based on using squid carcasses (dead bodies). The new, more accepted classification is most probably based on an analysis of (1) a greater number of squid carcasses (2) the feeding habits of the three different species (3) a number of newly found squid fossils (4) the DNA present in the cells of squid

4. the DNA present in the cells of squid