1.
A student used a microscope to observe several protists. The student sketched the protists and recorded their magnifications. The drawings and measurements are shown below.
Which of these protists is the largest?
Correct Answer
A. Difflugia
Explanation
A and B are magnified only 4 times, so they are larger than C and D, which had to be magnified 10 times to be seen clearly. Between A and B, A (Difflugia) appears the largest.
2.
What is the lowest level of the energy pyramid that contains carnivores?
Correct Answer
C. Level 3
Explanation
The lowest level of the energy pyramid that contains carnivores is Level 3. This is because carnivores are secondary consumers, meaning they feed on herbivores that are one level above them in the energy pyramid. Therefore, they are found at Level 3, which is the level above the primary consumers (herbivores) and below the top predators (tertiary consumers) at Level 4.
3.
Scientists classify humans as omnivores, based on their teeth. As omnivores, humans eat _____.
Correct Answer
B. Mostly plants and animals
Explanation
Think of the definition of an omnivore. That's all there is to it!
4.
How would the populations of other organisms in the energy pyramid be affected if the population of sea urchins suddenly decreased?
Correct Answer
D. The kelp population would increase, and the sheepHead population would decrease.
Explanation
Kelp increases because there are fewer sea urchins eating it. Sheephead population decreases because there are fewer urchins for food.
5.
On Earth, water cycles through the atmosphere, oceans, land, and organisms. By what process does most of the water in plants return to the environment?
Correct Answer
C. Evaporation from the leaves
Explanation
Roots are used to absorb water, not to release it into the environment, so a and d are incorrect. Condensation on leaves would bring water to the plant, but not return it to the atmosphpere. Evaporation from leaves is the only correct choice. This is also called transpiration.
6.
A drop of iodine is placed in a test tube containing a sample of an unknown solution. The solution turns blue-black. This indicates that the unknown contains _________.
Correct Answer
C. Starch
Explanation
The blue-black color formed when iodine is added to the unknown solution suggests that the unknown contains starch. Iodine reacts with starch to form a blue-black complex. This reaction is commonly used as a test for the presence of starch in various substances.
7.
A piece of potato is rubbed on a small sheet of brown paper. What would you expect to see?
Correct Answer
A. A wet spot
Explanation
Rubbing a piece of potato on a small sheet of brown paper would likely result in a wet spot. This is because potatoes contain a high amount of moisture, and rubbing it on the paper would transfer some of this moisture onto the paper, causing it to become wet.
8.
Cells, such as bacteria cells, which lack a membrane-covered nucleus and have few organelles, are called ________________.
Correct Answer
C. Prokaryotes
Explanation
Prokaryotes are cells that lack a membrane-covered nucleus and have few organelles. They are typically found in bacteria cells. Chloroplasts are organelles found in plant cells that are responsible for photosynthesis. Probiotic refers to live bacteria and yeasts that are beneficial for health. Eukaryotes are cells that have a membrane-covered nucleus and numerous organelles, and they include both plant and animal cells. Therefore, the correct answer is prokaryotes.
9.
Which of the following is a major component of cell membranes?
Correct Answer
B. Lipids
Explanation
Lipids are a major component of cell membranes. They form a lipid bilayer that surrounds and protects the cell, providing a barrier between the internal and external environment. Lipids are hydrophobic molecules, meaning they repel water, which helps to maintain the integrity of the cell membrane. They also play a crucial role in cell signaling, cell recognition, and the transport of molecules across the membrane. Therefore, lipids are essential for the structure and function of cell membranes.
10.
Which element, found in proteins, is NOT present in carbohydrates or lipids?
Correct Answer
D. Nitrogen/
Explanation
Nitrogen is the element that is not present in carbohydrates or lipids. Carbohydrates and lipids primarily consist of carbon, hydrogen, and oxygen. Nitrogen is a key component of proteins, which are made up of amino acids. Therefore, nitrogen is unique to proteins and is not found in carbohydrates or lipids.
11.
Bacteria in deep undersea thermal vents store energy using inorganic compounds, not light. This process is known as __________.
Correct Answer
A. Chemosynthesis
Explanation
The process described in the question, where bacteria in deep undersea thermal vents store energy using inorganic compounds instead of light, is known as chemosynthesis. Chemosynthesis is a process by which organisms convert chemical energy into organic compounds, without the need for sunlight. This process is commonly observed in environments where sunlight is not available, such as deep sea hydrothermal vents.
12.
Glucose is able to break down into two energy-packed ATPs without the help of oxygen in ______________ respiration.
Correct Answer
B. Anaerobic
Explanation
Anaerobic respiration refers to the process of breaking down glucose without the presence of oxygen. In this type of respiration, glucose is converted into two ATP molecules, which are energy carriers used by cells. This process is commonly observed in organisms that live in environments with limited oxygen availability, such as certain bacteria and yeast. By undergoing anaerobic respiration, these organisms are able to produce energy even in the absence of oxygen.
13.
A student places an Elodea plant in a test tube of water under a strong light. After a while the student notices tiny bubbles forming on the surface of the Elodea leaves. These bubbles likely contain mostly ___________.
Correct Answer
A. Oxygen
Explanation
The plant is giving off oxygen as a product of photosynthesis.
14.
During prophase I, sections of homologous chromosomes switch places.
What is this process called?
Correct Answer
C. Crossing over
Explanation
During prophase I of meiosis, homologous chromosomes pair up and exchange genetic material through a process called crossing over. This results in the rearrangement of sections of the chromosomes, leading to genetic variation in the offspring. Binary fission is a type of cell division in prokaryotes, mutation refers to a change in the DNA sequence, and cytokinesis is the division of the cytoplasm that occurs after nuclear division.
15.
A sperm cell of a fruit fly has 4 chromosomes. How many chromosomes are in the cells of a fruit fly’s leg?
Correct Answer
C. 8
Explanation
Sperm cells are haploid. Therefore the number of chromosomes is 1/2 that of the leg cell. To find the leg cell, we must multiply 4 by 2.
16.
In a species of fly, the allele for red eyes (R) is dominant to the allele for brown eyes (r). Red eye color in the flies is not sex-linked. Students crossed male and female flies that had red eyes and recorded the eye color of their offspring. Their data are shown below.
Fly Offspring
Eye Color
Number of Offspring
Red
77
Brown
27
What are the most likely genotypes of the parent flies?
Correct Answer
B. Rr
Explanation
The most likely genotypes of the parent flies are Rr. This is because red eye color is dominant to brown eye color, so both parents must have at least one copy of the dominant allele (R) in order for their offspring to have red eyes. Since the offspring include both red-eyed and brown-eyed flies, it is likely that one parent is heterozygous (Rr) and the other parent is homozygous recessive (rr).
17.
Which of the following processes occurs ONLY in plants?
Correct Answer
C. pHotosynthesis
Explanation
Photosynthesis is the process that occurs only in plants. It is the process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen. During photosynthesis, plants use chlorophyll to capture sunlight energy and convert it into chemical energy, which is stored in the form of glucose. This process is essential for plants to produce their own food and release oxygen into the atmosphere. Respiration, on the other hand, occurs in both plants and animals, while mitosis is a cell division process that occurs in all living organisms.
18.
In rabbits, short fur (F) is dominant to long fur (f). What are the chances that two heterozygous short-haired rabbits will have offspring with short fur?
Correct Answer
B. 75%
Explanation
When two rabbits are heterozygous for short fur (Ff), there are three possible genotypes for their offspring: FF, Ff, and ff. The dominant allele F will result in short fur, so both FF and Ff genotypes will have short fur. Only the ff genotype will have long fur. Therefore, 75% of the offspring will have short fur (FF and Ff genotypes), while 25% will have long fur (ff genotype).
19.
Oxygen levels increase in a pond during the day. This happens as a result of what process?
Correct Answer
C. pHotosynthesis
Explanation
During the day, plants in the pond undergo photosynthesis, a process in which they use sunlight, carbon dioxide, and water to produce oxygen and glucose. This leads to an increase in oxygen levels in the pond. Respiration, on the other hand, is the process by which organisms use oxygen to break down glucose and release energy. Replication is the process of copying DNA during cell division and is not related to the increase in oxygen levels in the pond.
20.
The following table provides data on the population growth of bacteria over time.
According to the data table, which of the following is true?
Correct Answer
B. The number of bacteria doubles every twenty minutes.
Explanation
The correct answer is "The number of bacteria doubles every twenty minutes." This can be inferred from the data table provided. The number of bacteria increases from 12 to 24 in 20 minutes, from 24 to 48 in the next 20 minutes, and so on. This consistent doubling of the bacteria population every 20 minutes indicates that the statement is true.