Science Flashcards

In the winter, people like to wear coats. Why is this?

Answer: Coats decrease the loss of body heat to surroundings through insulation.

Coats work by trapping a layer of air close to the body, which acts as an insulator. This insulation significantly reduces the rate at which body heat is transferred to the colder surroundings. Therefore, coats help maintain body temperature by decreasing heat loss, rather than generating heat or increasing the temperature of the cold air itself.

Which of the following is NOT true?

Answer: All organisms have a cell wall.

While all organisms are composed of cells and possess genetic material, not every organism has a cell wall. Animal cells, for example, lack a cell wall, having only a cell membrane. Cell walls are characteristic features of plant cells, fungi, bacteria, and some protists, providing structural support and protection.

The polar bear's dense fur and an exceptionally thick layer of fat under its skin protect it against the freezing temperatures of the habitat. How is natural selection in the evolution of a thick coat of fur in polar bears best explained?

Answer: Polar bears with thinner fur did not survive because they were not well suited to the environment.

Natural selection dictates that individuals with traits better suited to their environment are more likely to survive and reproduce. In a freezing habitat, polar bears with thinner fur would struggle to maintain body heat, making them less likely to survive and pass on their genes. Over generations, bears with thicker fur had a survival advantage, leading to the prevalence of this trait in the population.

Which of the following is a source of genetic variation within a species?

Answer: Mutation

Mutation is the primary source of new genetic variation within a species. These random changes in the DNA sequence can introduce new alleles and traits into a population. While other factors like natural selection act upon existing variation, mutations are responsible for creating the novel genetic material that drives evolution.

Rainfall in a tropical region is below average for 20 consecutive years. Animals adapted for dry conditions are much more plentiful at the end of the 20 years. Which of the following statements best explains the increase in the population of these animals?

Answer: Natural selection has favored insect species with a high tolerance for dry conditions.

This scenario exemplifies natural selection, where environmental conditions favor certain traits. When a region experiences prolonged dry conditions, insect species with a high tolerance for dryness are better adapted to survive and reproduce. Over 20 years, these favored individuals pass on their genes, leading to a significant increase in their population compared to less adapted species.

Which of the following sets of organisms would be found in a wetland ecosystem?

Answer: Salamander, mosquito, frog

Wetland ecosystems are characterized by abundant water, which is essential for the life cycles of amphibians and many insects. Salamanders and frogs are amphibians that typically lay eggs in water and thrive in moist environments. Mosquitoes also have aquatic larval stages, making them well-suited to wetland habitats.

Most bacteria cannot grow in high concentrations of salt. As a result?

Answer: salt acts as a preservative in many foods including dill, pickles, beef jerky, ham.

High concentrations of salt create a hypertonic environment, which draws water out of bacterial cells through osmosis. This dehydration inhibits the growth and reproduction of most bacteria, effectively preventing spoilage. This principle has been utilized for centuries as a method for preserving various foods like meats and vegetables.

There are four blood types in humans: A, B, AB, and O. An individual with blood type A has antibodies for B, so he or she can’t receive type B blood. Similarly, a person with blood type B has antibodies for type A and can’t receive type A blood. A person with AB blood type has no antibodies and can receive blood from anyone. A person with type O blood has both A and B antibodies and can receive blood only from someone else with type O blood. Based on this information, someone with type A blood can donate to?

Answer: Blood groups A and AB.

A person with type A blood has A antigens on their red blood cells and B antibodies in their plasma. They can donate blood to individuals who do not have antibodies against A antigens. This includes people with type A blood (who only have B antibodies) and people with type AB blood (who have no A or B antibodies).

Which of the following levels of organization best represents the sequence from smallest unit to largest?

Answer: Cell, tissue, organ, organ system

The biological organization of multicellular organisms follows a hierarchical structure. Cells are the fundamental units of life; similar cells group together to form tissues. Different tissues then combine to create organs, and multiple organs working in coordination constitute an organ system, representing increasing levels of complexity.

Grey fur color predominates over white fur color in mice. Two mice mate and have children; the female mouse has the genotype (gg), which causes white fur, while the male mouse has the genotype (Gg), which causes grey fur. Calculate the likelihood that these two mice will have offspring with white fur using the Punnett square.

Answer: 50%

To determine the likelihood of white fur offspring, we use a Punnett square with the parents' genotypes: female (gg) and male (Gg). The possible offspring genotypes are Gg, Gg, gg, and gg. This means 50% of the offspring will have the Gg genotype (grey fur) and 50% will have the gg genotype (white fur).

Earth's oceans are subject to tides, waves, and currents. These elements influence how humans interact with the ocean and how ocean water interacts with land. Tides are variations in ocean sea levels that occur on a regular basis. Which of the following factors contributes to ocean tides?

Answer: The gravitational pull of the moon on planet Earth

Ocean tides are primarily caused by the gravitational pull exerted by the Moon on Earth's oceans. The Moon's gravity creates bulges of water on both the side of Earth facing the Moon and the opposite side. These bulges result in the rhythmic rise and fall of sea levels that we observe as tides.

Yellowstone National Park is well-known for its various landscapes and diverse wildlife population. The Rocky Mountain wolf has maintained a long-standing predator-prey interaction with the park's deer. Grey wolves have been reintroduced in recent years to help diversify the animal population. What is the link between the Rocky Mountain and the Grey Wolf based on the chart?

Answer: Competition

The reintroduction of Grey wolves into an ecosystem already inhabited by Rocky Mountain wolves, with both species preying on deer, creates a competitive relationship. Both wolf populations will vie for the same limited resources, such as deer and territory. This struggle for shared resources is the definition of interspecific competition.

What type of simple machine is a seesaw an example of?

Answer: A lever

A seesaw is a classic example of a first-class lever, which is a type of simple machine. It consists of a rigid bar (the plank) that pivots around a fixed point called the fulcrum (the central support). When force is applied to one end, it causes the other end to move, demonstrating the principle of a lever.

What numbers should be filled in the blanks to balance the chemical equation?

Answer: 24, 8

To balance a chemical equation, the number of atoms for each element must be equal on both the reactant and product sides, adhering to the law of conservation of mass. The coefficients 24 and 8 would be placed in specific blanks within the equation to achieve this atomic balance. These numbers ensure that all atoms present before the reaction are accounted for after the reaction, just rearranged into new molecules.

As part of a study on how skin type and redness correlate when exposed to different amounts of UV light, a scientist set up an experiment to see how much redness occurred on different skin types. The scientist classified 100 people into six different skin type categories, then exposed them to increasingly higher doses of UV light and recorded the level of redness that appeared on the skin. In this experiment, which variables are independent and which are dependent?

Answer: An independent variable is the skin type; a dependent variable is the redness.

In this experiment, the independent variable is the factor intentionally manipulated or changed by the scientist, which is the different skin types. The dependent variable is the measurable outcome that responds to these changes, which is the level of redness observed on the skin. The amount of UV light would be a controlled variable, systematically applied to observe its effect on the dependent variable across different independent variables.

A cladogram is a graphic that categorizes organisms based on their similarities. It also depicts the evolutionary links between the groups. Which of the following claims is true based on the information in this cladogram?

Answer: Tomatoes and oranges share a common ancestor.

A cladogram illustrates evolutionary relationships, with each branching point representing a common ancestor. If tomatoes and oranges are shown to diverge from the same node on the cladogram, it indicates they share a common ancestor from which both lineages evolved. This placement signifies their evolutionary relatedness, even if they are not directly descended from each other.

Cold brew coffee is one of the hottest trends in coffee shops around the United States. It is commonly prepared by combining freshly ground coffee with cold water and allowing it to brew for 12 to 24 hours. One coffee shop experimented with pumping nitrous oxide into cold brewed coffee in the hopes of improving the taste. They discovered that the pressure of the nitrous gas had a profound effect on the flavor of the coffee as they experimented with this novel notion. At that time, they decided to conduct an experiment with three batches of coffee to determine the amount of pressure required to produce the greatest-tasting coffee. The provided chart depicts the methods that they followed for each batch. What was the problem with their experiment's design?

Answer: The coffee house should have used a set amount of time for brewing.

For an experiment to accurately determine the effect of nitrous gas pressure on coffee flavor, all other variables must be kept constant. If the brewing time varied between batches, it introduces another changing factor alongside pressure. To isolate the impact of pressure, the coffee house should have used a consistent, set amount of time for brewing all batches.

Researchers developed a method for forecasting the environmental impact of population growth: E = (P x N) ÷ T Where E stands for environmental effect, P is for population, N stands for energy consumption, and T stands for technological advancement. According to the equation, what element must change at a rate equal to the rate of population growth in order to sustain population expansion and maintain environmental impact?

Answer: An increase in technology

The equation E = (P x N) ÷ T shows that environmental effect (E) is inversely proportional to technological advancement (T). To maintain a stable environmental impact (E) while the population (P) increases, the rate of technological advancement (T) must increase proportionally. This ensures that technological improvements can offset the growing environmental strain from population and energy consumption.

The tendency to resist change in order to maintain a stable, relatively consistent internal environment is referred to as homeostasis. Negative feedback loops are commonly used in homeostasis to counterbalance changes in various attributes from their goal values, known as set points. Which of the following best defines the feedback system utilized by a healthy individual to control body temperature in both warm and cold environments?

Answer: When body temperature is too high, the body starts to sweat in order to cool; when the body temperature becomes too low, the body starts shivering in order to warm up.

Homeostasis uses negative feedback loops to counteract deviations from a set point. When body temperature is too high, the body sweats to cool down through evaporation. Conversely, when body temperature is too low, the body shivers to generate heat through muscle contractions, warming itself back up to the set point.