1. The tropical regions are subjected to extreme changes of season.
2. The polar regions were populated earliest in the history of Earth.
3. The polar regions receive more intense solar energy.
4. The tropical regions contain more micro-ecosystems.

1. The extinction rates calculation method should be adopted. It uses species-area curves that overestimate rates of extinction. The rate of habitat destruction calculation method uses large numbers of measurements, but it overestimates the rate of extinction.
2. The rate of habitat calculation method should be adopted. It is based on a large number of observations and measurements, but it overestimates the rate of extinction. The extinction rates calculation method uses species-area curves, but it underestimates the rate of extinction.
3. The extinction rates calculation method should be adopted. It is based on a large number of observations and measurements, but it overestimates rates of extinction. The rate of habitat destruction calculation method uses species-area curves, but it underestimates the rate of extinction.
4. The rate of habitat destruction calculation should be adopted. It uses species-area curves, but it overestimates the rate of extinction. The extinction rates calculation method is based on a large number of observations and measurements, but it underestimates rates of extinction.

What evidence do scientists provide for the cause of the Cretaceous–Paleogene mass extinction.

1. The unusual abundance of iridium in the Cretaceous-Paleogene layers, the disappearance of so many species at its transition, volcanic activity that led to global warming, and the crater found in the Yucatan peninsula.
2. The unusual abundance of iridium in the Cretaceous-Paleogene layers, gamma-ray burst caused by a nearby supernova, rocks found in the clay layer at its boundary, and the crater found in the Yucatan peninsula.
3. The unusual abundance of iridium in the Cretaceous-Paleogene layers, the disappearance of so many species at its transition, rocks found in the clay layer at its boundary, asteroid impact, and volcanic eruptions at large.
4. The unusual abundance of iridium in the Cretaceous-Paleogene layers, the disappearance of so many species at its transition, rocks found in the clay layer at its boundary, and the crater found in the Yucatan peninsula.

1. Madagascar has a climate that is more conducive to evolution than the larger African continent.
2. Madagascar is close to the tropics of Africa and consequently has a large number of species.
3. Madagascar shows species diversity of both temperate and tropical regions.
4. Madagascar has been isolated geographically and species evolved there without interaction with outside influences.

1. Compounds similar to the snake’s active toxin are used routinely as antivirals. Opioids are used as immunomodulators, which modify an immune response.
2. Compounds similar to the snake’s active toxin are used routinely as painkillers. Opioids help in the lowering of blood pressure.
3. Compounds similar to the snake’s active toxin are used to treat inflammations. Opioids are used to prevent muscle spasms.
4. Compounds similar to the snake’s active toxin are used to lower blood pressure. Opioids are used routinely as painkillers.

1. Loss of wild species would result in inbreeding depression, as crop varieties must be bred with wild species to remain viable.
2. Loss of biodiversity reduces large-scale monocultures but reinforces genetic homogeneity contributing in the loss of crop diversity.
3. Loss of wild species would result in an increase of intraspecific diversity within the different crop varieties, but decrease in interspecific crop diversity.
4. Loss of wild species would reduce the genetic variations as genes from wild relatives are brought into crop varieties to add valued characteristics to crops.

1. Only pharmaceutical manufacturing and industries involved in honey production would be affected.
2. Other pollinators would replace the bees in the ecosystem, and there would probably not be a major impact on the production of produce.
3. Lack of pollinators would affect the honey industry, but not the fruit harvest industry, because other pollinators would be present to carry out pollination.
4. The lack of pollinators would affect the fruit harvest directly, and it indirectly would affect industries linked to it, such as the honey and jam preparation industries.

1. Because plants have to protect themselves year-round, as cold spells in winter do not kill pests as they do in temperate areas
2. Because the plants must protect themselves from insects as repellants and toxins sprayed by humans do not work in tropical areas
3. Because the compounds produced to kill insects also enhance the ability of the plant to recover from damage caused by various phenomena
4. Because compounds produced to kill insects also influence the behavior and growth of tropical plants

1. Human population growth leads to unsustainable resource use, habitat destruction, and the unsustainable fishing and hunting of wild animal populations. All these incidences result in a slow evolutionary rate of formation of new species
2. Human population growth leads to unsustainable resource use, habitat destruction, and the unsustainable fishing and hunting of wild animal populations. Climate change also occurs due to excessive use of fossil fuels
3. Human population growth leads to unsustainable resource use, habitat destruction, and unsustainable fishing and hunting of wild animal populations. Excessive use of fossil fuels is leading to reduced populations of fish species
4. Human population growth leads to unsustainable resource use, habitat destruction, and unsustainable fishing and hunting of wild animal populations. Larger human populations are also leading to decreased value of products obtained from species

1. The frog is at risk from climate change, habitat destruction, and aggressive predators.
2. The frog is at risk from climate change, exotic species, and possible habitat destruction.
3. The frog is at risk from climate change, habitat destruction, and sparse availability of food.
4. The frog is at risk from climate change, exotic species, and overhunting in its habitat.

1. Through the air
2. Through contaminated food and water
3. Through direct human contact from increased presence in wilderness areas
4. Through vectors such as mosquitoes

1. The disappearance of top predators results in excessive multiplication of producers. Producers will overgraze primary consumers.
2. If a top predator disappears, the primary consumers will multiply without restriction, but producers will not be affected.
3. If a top predator disappears, producers will multiply without restriction.
4. The disappearance of top predators results in excessive multiplication of primary consumers. Primary consumers will overgraze producers.

1. The rhinoceroses are hunted in their native countries, but the trade crosses borders.
2. The use of rhinoceros horns as an aphrodisiac has shown various negative effects internationally.
3. The hunters from different countries travel to the native country to hunt for rhinoceroses.
4. The demand for rhinoceroses is greater in foreign countries as compared to their native countries.

1. Set up many, small, protected areas.
2. Select one, small area that is isolated from residences.
3. Plan buffer zones around all backyard spaces.
4. Set up several larger areas to be set aside for natural ecosystems.

1. Many species would increase and the elk population would disappear.
2. Many species would disappear and the elk population would initially increase.
3. Many species along with elk population would initially increase.
4. Many species, along with the elk population, would disappear rapidly.

1. Signatory nations follow through with their good intentions. No governing body enforces international environmental protection.
2. Signatory nations do not follow through with their good intentions. A governing body enforces international environmental protection.
3. Signatory nations do not follow through with their good intentions. No governing body enforces international environmental protection.
4. Signatory nations follow through with their good intentions. A governing body enforces international environmental protection, but neither is effective.