1. 39. The finch beak adaptations in the graphic most likely evolved through the mechanism of
The correct answer is
A stabilizing selection
B adaptive radiation
C genetic drift
D non-random mating

2. EXPLANATION
The correct answer is B adaptive radiation because when an organism arrives in a new environment, such as the Galapagos Islands were, it adapts through natural selection to fill all of the available niches, resulting in a variety of related species
Stabilizing selection is when there is less variation in a trait due to natural selection. A example of this is human birth weight. Babies below and above a certain weight don’t survive, so you get a narrow curve on the graph.
Genetic drift is change in gene frequency in a population due to chance, such as in founder effect or population bottleneck.
Non-random mating refers to there being a preference for certain traits in mates.

3. 40. Species become more diverse to. I. Occupy available niches. II
40. Species become more diverse to   I. Occupy available niches II. Reduce competition III. Adapt to changing environmental conditions
The correct answer is
A I and II only
B I and III only
C II and III only
D I, II, and III

4. EXPLANATION
The answer is D, I, II, and III because all three of those explain why there is diversity or variation within a species.
An available niche is a habitat that is available, including resources in which an organism can “make a living”
Reducing competition means that an organism is one of a very few if not the only one wanting a particular resource like food, water, or space
Adapting to changing environmental conditions refers to the process of natural selection that results in change in gene frequency

5. Laugh Break! We hope you have no days like this:

6. 41. Given the characteristics described in the information box , this species belongs in kingdom
The correct answer is
A Archaebacteria
B Fungi
C Eubacteria
D Protista
Characteristics of species
Unicellular
Nucleated cells
Microscopic
Motile
Inhabits aquatic environments

7. EXPLANATION
ANSWER D-Protista is the correct answer by default because it can’t be any of the other three. Archaebacteria and Eubacteria are the 2 kingdoms of prokaryotes and they don’t have nucleated cells. Fungi aren’t motile and are rarely unicellular (only the yeast are).
Remember – it’s the junk drawer of classification!

8. 42. The organism pictured, Escherichia coli, is a common symbiont in mammalian digestive systems. This organism has a circular chromosome located in a region of the cell called the nucleoid (A), a rigid outer cell wall (B), and a semi-permeable cell membrane (C). To which kingdom does this organism belong?
The correct answer is
A Archaebacteria
B Eubacteria
C Protista
D Fungi

9. EXPLANATION The correct answer is B Eubacteria because
Archaebacteria aren’t known symbionts, and
Protista and Fungi are eukaryotes, which means they will have linear chromosomes in a nucleus, not a circular chromosome in the nucleoid region.

10. 43. Fungi are unique among eukaryotes in that they are
The correct answer is
A unicellular
B multicellular
C autotrophic
D decomposers

11. ANSWER D-EXPLANATION
The key word here is “unique”. In the eukaryotes, the protists are also unicellular; both animals and plants as well as some protists are multicellular, and some protists and all plants are autotrophs (which fungi aren’t, by the way, they’re heterotrophic by absorption). Only fungi are decomposers (along with the prokaryotic bacteria!)

12. 44. The animal species in the illustration has the following characteristics; it breathes with lungs, maintains a constant body temperature, has hair, gives live birth, and nurses young with milk. These characteristics place the animal in the class
A Amphibia
B Aves
C Mammalia
D Osteichthyes

13. C-EXPLANATION Mammalia (mammals) Body covered in hair Amphibia
(amphibians)
Cold- blooded
Smooth skin
Gills in young, adults respire through lungs, skin
Aves
(birds)
Warm-blooded
Body covered in feathers
lungs
Mammalia
(mammals)
Body covered in hair
Osteichthyes
(bony fish)
Cold-blooded
Body covered in scales
gills
Chondrichthyes
(cartilaginous fish)
Reptilia
(reptiles)

14. SCIENCE!

15. 45. The simple sugar glucose, C6H12O6 , is formed through the process of photosynthesis as depicted in the chemical equation. Simple sugars are unique among bio-molecules in that
The correct answer is
A they are used by the body for long-term energy storage.
B they do not dissolve readily in water.
C carbon, hydrogen, and oxygen atoms are always found in a 1:2:1 ratio.
D they are the building blocks of proteins.

16. EXPLANATION
A is incorrect because it’s FAT that is used for long- term energy storage
B is incorrect because sugar will dissolve in water
D is incorrect because it is AMINO ACIDS that are the building blocks of proteins.
C is correct because 6:12:6 reduces to 1:2:1

17. 46. When comparing the reactants and products of photosynthesis and cellular respiration, which statement is true?
The correct answer is
A Carbon dioxide is a product of photosynthesis.
B Oxygen is a product of cellular respiration.
C Solar energy is converted to chemical energy in the process of photosynthesis.
D Energy is stored in the bonds of glucose in the process of cellular respiration.

18. ANSWER C-EXPLANATION
As you can see, the light energy that powers photosynthesis is ultimately stored in the bonds of ATP for cellular use.

19. 47. When compared to the process of photosynthesis, cellular respiration produces more   I. ATP II. CO2 III. O2
The correct answer is
A I only
B II only
C I and II only
D I and III only

20. ANSWER C-EXPLANATION

21. 48. Enzymes are proteins which function in both catabolic and anabolic pathways in living things. Which of the following is NOT a characteristic of enzymes?
The correct answer is
A Enzymes act as biological catalysts.
B Enzymes slow down chemical reactions.
C Enzymes reduce activation energy needed for a chemical reaction to proceed.
D Enzymes are re-usable.

22. EXPLANATION
We typically describe enzymes as speeding up reactions, which is why B is NOT a characteristic.
Enzymes are catalysts, which by definition are not changed or used up (A and D); see picture above
Enzymes reduce activation energy (C); see graph

23. 49. Polymers such as proteins, lipids, amino acids, and carbohydrates are formed when individual monomers are joined through the process of dehydration synthesis. Dehydration synthesis requires the
A loss of a water molecule
B destruction of a water molecule
C evaporation of a water molecule
D addition of a water molecule

24. A-EXPLANATION Word Parts: de – to remove hydro – water syn – together
Dehydration synthesis reactions lose a molecule of water when a bond is formed between 2 molecules.
Dehydration synthesis reactions can form polysaccharides (carbohydrates), nucleic acids, proteins, and some lipids

25. 50. Which of these best describes how human body systems interact to protect the body from injury or illness?
The correct answer is
A The skeletal system releases calcium ions into the organs of the respiratory system to encapsulate bacteria and viruses in the lungs.
B Immune system B-cells are produced in the bone marrow of the skeletal system and introduced into the blood stream.
C The nervous system stimulates the digestive system to release toxins that kill invading microbes.
D Hormones released by viruses increase both blood pressure and body temperature which work to inactivate them.

26. EXPLANATION
A, C, and D all describe things that do not happen in the human body.
B describes an immune response such as is pictured (swelling, redness, arrival of WBCs, etc)

27. We love you 

28. 51. Which is the best description of how the organ system pictured interacts with the circulatory system to deliver nutrients to cells?
A Nutrients are taken in through the respiratory system and are picked up by the thin walls of capillaries in the lungs for delivery to the rest of the body’s cells.
B The digestive system processes food into smaller molecules which are picked up for delivery to the body’s cells by the circulatory system through capillaries in the small intestine.
C The circulatory system moves the secretions from the liver, gallbladder, and pancreas through the bloodstream for delivery to the stomach where they are used to break down large particles.
D Water recovered from the large intestine is picked up by capillaries and delivered to the stomach to aid in digestion.

29. EXPLANATION
A is incorrect because nutrients are not taken in through the respiratory system
C is incorrect because the products of those accessory organs do not enter the circulatory system and do not enter the stomach (they go to the small intestine through a duct)
D is incorrect because the water is not delivered to the stomach
All of choice B is accurate.

30. 52. Which is the best explanation of how the muscular system aids in delivering nutrients to cells?
The correct answer is
A Layers of smooth muscle line the organs of the digestive system, pushing the meal through the system by involuntary contractions known as peristalsis.
B Teeth mechanically break down food into smaller pieces so enzymes in the digestive system have a larger surface area to work on.
C Microvilli in the small intestine have a large surface area for small molecules to diffuse from the digestive system into the bloodstream.
D Large muscles require large amounts of energy to do work.

31. EXPLANATION
What’s tricky here is that all 4 answer choices are correct statements; however, only A answers the question!
To the right is a picture of peristalsis – the rhythmic contractions of involuntary muscle to move particles along a tract

32. 53. Which is the best description of the interactions of plant organ systems to produce the response illustrated?
The correct answer is
A Stem tips produce a growth hormone which travels through phloem tissues to other parts of the plant where it causes elongation of cells on the dark side of a stem.
B Leaves which receive excess sunlight produce a wilting hormone that travels to other parts of the plant through vascular tissues.
C Bright days cause leaves to lose water rapidly, which draws water up from the roots through vascular tissues at such a pace that stems bend due to the increased water weight.
D Certain chemical substances in the air are taken into leaves through stoma and as they are carried downward through vascular tissues in the stem the increased weight causes stems to bend.

33. EXPLANATION
The picture illustrates phototropism – a plant’s response to light. Other tropisms include:
Geotropism or gravitropism – roots grow down and shoots grow up
Thigmotropism – vines cling and coil in response to touch
Choice A accurately describes what happens when a plant is exposed to light.
Photo – light
Tropism – response to a stimulus
Positive – toward the stimulus
Negative – away from the stimulus
There is no wilting hormone, that’s just a lack of water; water and chemicals do not weigh plants down

34. Laugh Break!

35. 54. Glucose produced by photosynthesis is stored as starch in storage organs such as potatoes, onions, and carrots. Which of these is NOT part of the plant system interactions involved in this process?
The correct answer is
A Leaves produce the sugar glucose through photosynthesis.
B Sugars produced by leaves are moved from sink to source by xylem vessels.
C Sugars produced by leaves are moved from source to sink by phloem vessels.
D Root systems store glucose as starch.

36. EXPLANATION
B is an incorrect statement because sugar does not move in xylem and because it moves from the source to the sink, not sink to source.
Water is carried in Xylem – WXY
Phloem carries phood (food)

37. 55. Which is the most correct description of two plant systems interacting to perform the function of reproduction in angiosperms?
The correct answer is
A Carbon is obtained from the air as CO2 through stoma in the leaves to build all of the macromolecules needed for reproduction.
B Carbon is obtained from the soil through the root systems and delivered with water and other nutrients to reproductive organs.
C Most water is obtained in the form of water vapor through leaf pores and delivered through phloem tissues to reproductive organs.
D Most water is absorbed directly through stoma during rain events and transferred to all parts of the plant by phloem tissues.

38. EXPLANATION
A is the correct answer because CO2 enters through the stomata
B is incorrect because carbon comes from CO2 not from the soil
C is incorrect because very little if any water comes from water vapor and it moves in xylem
D is incorrect because water doesn’t enter during rain events and moves in xylem

39. 56. Which term contains all of the others?
The correct answer is
A tissue
B organ
C organ system
D cell

40. EXPLANATION
“contains all the others” means they want to know if you choose one of those four things, which one would give you all of them
If you choose organ system, you will have organs in your system, you will have tissues making up your organs, and you will have cells making up your tissues

41. 57. Which of the following statements is least accurate in describing internal feedback mechanisms?
The correct answer is
A The excretory system plays a major role in controlling water balance, salt concentrations in the blood, and removing nitrogenous wastes.
B An imbalance in blood sugar regulation by the competing hormones insulin and glucagon may result in the disease diabetes.
C Cold-blooded organisms expend less energy than warm-blooded organisms because they lack control mechanisms to maintain body temperature.
D Positive feedback mechanisms work to maintain levels within a narrow window of parameters, whereas negative feedback mechanisms push levels beyond the normal range.

42. EXPLANATION
Negative feedback is like how a thermometer works. You set it to produce air at a certain temperature and when the air is hotter or colder than that, it will come on and work to return the air to the temperature you set it at. Your body temperature is regulated in a similar way. Your blood sugar level is regulated through negative feedback, too.
Positive feedback is like how praise is supposed to work. You do something good and somebody gives you praise and you want to do more good so you get more praise so you do more good… A biological example is childbirth. Pressure on the cervix releases hormones that cause contractions that put pressure on the cervix that release hormones that cause contractions…
D is exactly the opposite of this so it is the LEAST accurate
A, B, and C all relate to feedback mechanisms in the bodies of animals

43. 58. Microorganisms such as E
58. Microorganisms such as E. coli inhabit the digestive systems of a variety of higher organisms, including humans. These endosymbionts help their hosts maintain health by all of these EXCEPT
The correct answer is
A breaking down food
B producing key nutrients
C infecting adjoining tissues
D competing with harmful microorganisms

44. EXPLANATION
E. coli are very important to our digestive health. One of the most important things they do is aid in vitamin K synthesis, which is essential for blood clotting.
All of our natural symbionts, such as E. coli, help to outcomplete pathogenic microorganisms
Our natural symbionts do not cause infection in healthy individuals

45. 59. As the process of ecological succession progresses with time, species diversity tends to
The correct answer is
A gradually decrease from colonization to climax community
B be limited in early stages and increase over time
C increase during intermediate stages, then rapidly decrease during the climax community stage
D be highest in the colonization stages

46. EXPLANATION
Ecological succession is the theory that species replace other species over time as the environment changes until a stable ecosystem is developed. The stability comes from the interaction of a diverse and large number of organisms in the climax community.
Diversity increases with succession, it does not decrease

47. 60. Which of these statements best summarizes the change in populations which has occurred during the stages of succession illustrated above?
The correct answer is
A Populations of freshwater fish and aquatic plants are gradually replaced by populations of weeds and grasses as a pond fills with silt.
B A terrestrial ecosystem is replaced by a freshwater ecosystem.
C A marine ecosystem is replaced by a terrestrial ecosystem.
D Populations of freshwater fish and aquatic plants die off as their habit becomes filled with silt.

48. EXPLANATION
A is correct because what you see is a pond with fish and aquatic plants that gets shallower and shallower until it is filled with dirt (silt) and different plants are growing there
B and C are completely inaccurate and not supported by the diagram
D is not the right answer because it is incomplete

49. Your parents love you, too!

50. 61. Eliminating microorganisms from an ecosystem would have all of the following effects EXCEPT
The correct answer is
A increased carbon dioxide available to plants
B plants starved of key nitrogen-containing nutrients
C food chains disrupted
D decomposition would halt

51. EXPLANATION the key word is EXCEPT If microorganisms are eliminated :
the nitrogen cycle would be interrupted because bacteria are the key to the nitrogen cycle processes
Food chains would be disrupted because the smallest organisms feed on the microorganisms, so they would die, which means the larger ones would die; AND the plants would die because of the lack of nitrogen in the soil so the herbivores would die
Bacteria are principal decomposers (along with the fungi) so there would be a tremendous impact on this process
The CO2 available to plants would not change or would actually decrease because of the lack of decomposition, but it would not increase

52. 62. Termites are incapable of digesting the wood fibers they ingest, but maintain a population of symbiotic bacteria in their gut which break down the wood fiber for them. This relationship is best described as
The correct answer is
A parasitism
B mutualism
C predation
D commensalism

53. EXPLANATION Parasitism:  on host Mutualism:  on host
Predation: one organism eats another organism (predator and prey)
Commensalism: no effect on host
This relationship is mutualism because both the host (termite) and the bacteria are benefitting from the relationship

54. 63. The deer tick must feed on the blood of warm- blooded mammals in order to survive. At times, as the tick feeds it also transmits harmful bacteria to the host which cause lyme disease. This relationship is an example of
The correct answer is
A parasitism
B mutualism
C predation
D commensalism

55. EXPLANATION
Ticks suck the blood from their host to steal nutrients from them – this is a negative effect
Ticks that cause diseases like Lyme disease have an even more negative effect
When the host is negatively impacted  the relationship is parasitism

56. 64. Based on the adaptations listed in the table above, which organism is best suited for life in the tropical rainforest ecosystem?
The correct answer is
Snowshoe hare
Kangaroo rat
Prairie dog
Tarsier

57. EXPLANATION
Fur, reduced ears, and changing colors in seasons are adaptations of animals that live through long cold winters, not tropical rainforests
Small bodies, large ears, burrowing, and concentrated urine are adaptations of desert animals
Eating grass, burrows, strong hind legs, and water from food are adaptations for a temperate grassland
Living in trees, eating bugs at night, and having excellent climbing and jumping skills are adaptations suitable for tropical rainforests

58. 65. In the food web, which organisms are most likely to become overpopulated if there were a larger than average production of seeds during a growing season?
The correct answer is
A grouse
B chipmunk
C elk
D grizzly bear

59. EXPLANATION
Grouse is correct because it eats the seeds, but has no predators keeping its population in check, unlike the chipmunks.

60. 66. What is the best explanation of why the numbers of organisms at each trophic level decrease from the bottom of the pyramid to the top?
The correct answer is
A The organisms increase in size as you move up the pyramid.
B Energy is used for life processes and lost as heat at each trophic level.
C Energy is wasted at each trophic level.
D There is more sunlight available to the first trophic level.

61. EXPLANATION
A and D are true statements, but do not explain the pyramid.
C is not a true statement
B is the correct answer . Recall that only 10% of the energy on the previous trophic level is passed to the next, so with less energy available, fewer organisms are supported

62. 67. Carbon flows cyclically through organisms and the environment
67. Carbon flows cyclically through organisms and the environment. Which of the following descriptions of the carbon cycle is NOT correct?
The correct answer is
A Major reservoirs of carbon include tropical forests, oceans and fossil fuels.
B Carbon dioxide is produced through photosynthesis and used in cellular respiration.
C Humans may disrupt the carbon cycle by burning fossil fuels which may result in global warming.
D Carbon is released to the atmosphere in the form of CO2 through respiration in living things.

63. EXPLANATION
A, C, and D are all true statements about carbon and the carbon cycle; B is the correct answer because it is the reverse of that – CO2 is produced in respiration and used in photosynthesis

64. 68. In an ecosystem, the simple food chain above shows the movement of matter and energy from one organism to the next. If disease reduced the number of organisms at the producer level, which other organism would feel the greatest effect?
The correct answer is
A the mouse because it is a producer
B the mouse because it eats producers
C the cat since it is a 2nd order consumer
D the coyote because it is the top consumer in the food chain

65. EXPLANATION
Because the coyote is receiving less energy than any other organism in the food chain because only 10% is passed up at each level, it would be the most impacted.
If there are fewer plants, fewer mice will survive, but some will. If a few mice survive, very few cats will survive, but some will; and finally, if a very few cats survive, very very few coyotes will.
Don’t overthink the question. It is asking about THIS FOODCHAIN, not any other organism that may or may not exist in the ecosystem.

66. 69. The graph depicts the growth of a population of yeast cells over time. The dotted line labeled A most likely represents
The correct answer is
A the limit of tolerance of the yeast cells to environmental conditions
B the highest number of yeast cells the population can achieve
C the carrying capacity of the environment
D population size of a predator which preys on the yeast

67. EXPLANATION A B
On a population graph, a horizontal line typically represents carrying capacity (K). Carrying capacity is the number of organisms of one species the resources in an environment can support.
A is incorrect because it says the limit of tolerance, and that’s not what carrying capacity measures; highest number of yeast cells the population can achieve is not accurate either
D has nothing to do with the graph

68. A Carrying capacity of the environment increased.
Use the information in the following paragraph for the next question Throughout the decade of the 1930’s, a series of severe dust storms blew across the prairie lands of the United States, causing extreme ecological and agricultural damage.  Years of poor farming practices and drought resulted in the loss of tons of topsoil to prevailing winds.  Millions of acres of land became barren and uninhabitable. 70. Which is the best description of how this event likely impacted the natural prairie ecosystem that inhabited the area?
The correct answer is
A Carrying capacity of the environment increased.
B The mature prairie community was replaced with weedy species.
C Biodiversity increased.
D Primary succession occurred.

69. EXPLANATION
In the information given, it is stated that “Years of poor farming practices and drought resulted in the loss of tons of topsoil to prevailing winds. Millions of acres of land became barren and uninhabitable.”
The loss of topsoil will require D, primary succession.
B can be argued, but the question states that the land was barren and uninhabitable – that means not even weeds would grow. They might have during the process, but the final result would have been nothing left.
A and C do not make sense with the information given

70. You can do this! We know you can!

71. 71. Which of the following most accurately shows diffusion ?
The correct answer is A

72. EXPLANATION
Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
B is showing the reverse of that (which can’t happen in nature); C & D are not showing anything happening.

73. 72. The rough ER is represented by which letter ?
The correct answer is
A. 2 B. 3 C. 5 D. 6
73. The organelle where cellular respiration takes place and glucose is converted into ATP energy is represented by
The correct answer is
A. 2 B. 4 C. 5 D. 6

74. EXPLANATION 1 – cell/plasma membrane – homeostasis
2 – rough ER – transport of materials through cell; protein synthesis
3 nucleus – protects the DNA
4 ribosome – site of protein synthesis; made in nucleolus
5 smooth ER – lipid synthesis
6 mitochondria – cellular respiration; ATP production
7 vacuole – storage OR
vesicle – moving things from one organelle to another; endo- and exocytosis
EXPLANATION 1 2 3 4 5 6 7
Typical Animal Cell

75. 74. A herbicide is sprayed on foliage to eliminate weedy plants
74. A herbicide is sprayed on foliage to eliminate weedy plants. This herbicide remains on the leaves of sprayed plants, is ingested by grasshoppers and accumulates in their tissues. Songbirds then feed on the grasshoppers and the herbicide accumulates in their tissues. Finally, the coyote feeds on songbirds and the herbicide accumulates in the coyote’s body. At which trophic level do the toxins become most concentrated?
The correct answer is
A producers
B primary consumers
C secondary consumers
D top consumers

76. EXPLANATION This phenomenon is called biological magnification.
When a toxin like DDT or a heavy metal like lead or mercury gets into the environment, only a few molecules enter the bodies of microorganisms, but the larger animals consume multiple organisms at the level below them, increasing the concentration of those molecules in their bodies.
Since these are substances that can’t be excreted, they build up to tremendous levels at the top of the food chain

77. 75. A butterfly population has 2 alleles for wing color, pink (gg) and green (GG or Gg). The butterflies spend most of their time during the day in the canopies of trees. As a result the pink butterflies are much less common than the green butterflies due to predation by birds, lizards, and other predators. This is an example of
The correct answer is
A development of the butterfly due to hormonal action
B natural selection due to varying survival rates of the two colors of butterflies in the population
C maturation of the butterfly as it metamorphosis into a sexually mature adult
D extinction as the pink butterfly becomes rarer and rarer

78. EXPLANATION
Choices A and C are not correct because there is nothing in the question to indicate that the butterfly is developing or maturing.
D is not correct because the pink butterfly is unlikely to become extinct due to the fact that the recessive allele is maintained in the heterozygote
B explains why the green butterflies are common and the pink ones are rarer.

79. We would LOVE for you to know everything!

80. This is how we hope you feel during the EOC!
The End!