Download Midterm Study Guide Answers

7th GRADE LIFE SCIENCE
MID-TERM EXAM STUDY GUIDE
1. What elements are found in all living organisms (NCHOPS CaFe)?
 Nitrogen
 Phosphorous
 Carbon
 Sulfur
 Hydrogen
 Calcium
 Oxygen
 Iron
2. What are the four organic compounds?
 Lipids
 Proteins
 Carbohydrates
 Nucleic acids
3. Know examples and functions of the carbohydrates, lipids, proteins, and nucleic acids.
 Carbohydrates –
 Lipids –
 Proteins –
 Nucleic acids –
4. What organisms are prokaryotic cells? What organisms are made of eukaryotic cells?
 Prokaryotic cells
 Eukaryotic cells
5. Which cell has a nucleus? Which cell does not have a nucleus?
 Prokaryotic does not have a nucleus
 Eukaryotic cells DO have a nucleus
6. Which cell has membrane covered organelles? Which cell does not have membrane covered
organelles?
 Eukaryotic cells have membrane bound organelles, prokaryotic cells do not.
7. What are the similarities between the prokaryotic and the eukaryotic cell?
 Basic building blocks of life
 Both contain DNA
 Both divide
8. What determines the structures of living things?
 cells
9. What are the functions of an organism?
 The processes that enable it to live, grow, and reproduce
10. What must a cell do in order to stay alive?
 Obtain oxygen, food, and water, and get rid of wastes
11. How are organisms and cell similar?
 Cells must carry out all of its functions to keep the organisms alive
12. Who was Robert Hooke and why is he important?
 First discovered cells
 Viewed cork cells under a microscope and called them “small rooms”
 Gave cells their names
13. Who was Anton van Leeuwenhoek and why is he important?
 Built his own microscope, viewed living cells called him “animalcules”
 Revealed that cells moved and were smaller than the eye could see
14. What does the cell theory state?
 All living things are composed of cells
 Cells are the basic units of structure and function of living things
 All cells are composed from other cells
15. What scientists contributed to the cell theory? How did they learn from each other?
 Schleiden, Schwann, Virchow
 They all built off one another (see textbook, page 125)
16. Why did the cell theory take so long to create?
 microscopes back then weren't as strong as today, so you couldn't see as much. It took a long
time until enough knowledge of the cells arose in order to come up with the cell theory.
17. Why was the microscope important to the cell theory?
18. Why is an electron microscope better than a light microscope?
 Electron microscopes allow higher magnification and better resolution than light
19. How has technology affected human knowledge about cells over the past 300 years?

20. How are the cell wall and the cell membrane alike? How are they different? (p131)
 Both surround cells
 All cells have cell membranes
 Only plant cells have cell walls
 Allow materials to pass though
21. Why is the nucleus referred to as the brain of the cell?
 It directs all of the cells activities
22. Why is chromatin important to the nucleus?
 Contains info direction cell’s function
23. Where are ribosomes made?
 nucleolus
24. What organelles are suspended in the cytoplasm?
 Mitochondria, ER, ribosomes, Golgi apparatus, vacuole, lysosomes, chloroplasts
25. Why is the mitochondria called the powerhouse of the cell?
 Convert energy in food to energy used by the cell
26. What does the Endoplasmic Reticulum help the ribosomes do?
 Helps attached ribosomes make proteins
27. How is the Golgi apparatus like a warehouse?
 Packages and distributes materials from the ER
28. Why is the chloroplast so important to a plant cell?
 Makes food for the cell from energy from sunlight
29. What is the function of the lysosome?
 Breaks down food particles and worn out cell parts
30. How are plant and animal cells alike? How are plant and animal cells different?

31. What is a specialized cell? What are some examples of specialized cells and the functions of those
cells?
 Cells that erform specific functions that benefit the entire organism
 Ex. Red blood cells carry oxygen to other cells that may be busy digesting food
 Ex. Nerve cells help transmit information from one part of your body to another
32. Explain the level of organization in a multicellular organism. Be able to draw a diagram representing
the levels of organization.

33. How is the cell membrane selectively permeable?
 Some substances can cross while others cannot
34. How was the plastic bag like the cell membrane during the investigation?
 The plastic bag was selectively permeable by allowing the iodine to pass through but not the
water
35. What is passive transport?
 The movement of dissolved materials across a cell membrane without using the cell’s energy
36. What are the three types of passive transport?
 Diffusion, osmosis, facilitated diffusion
37. How are oxygen and carbon dioxide transported into and out the cell?
 diffusion
38. How is sugar transported into and out of the cell?
 Facilitated diffusion
39. How is water transported into and out of the cell?
 Osmosis
40. What is active transport?
 The movement of materials across a cell membrane using cellular energy
41. How are sodium, potassium, and calcium transported into and out of the cell?
 Active transport
42. What is the difference between passive and active transport?
 Passive moves from an area of high concentration to an area of low concentration
 Active moves from an area of low concentration to an area of high concentration
 Passive does not require energy, active does require energy
43. What is an autotroph? What is a heterotroph?
 Autotroph – an organism that makes its own food, or a producer
 Heterotroph – an organism that obtains food by eating other organisms
44. What is photosynthesis?
 The process by which a cell captures energy and uses it to make food
45. What happens during stage one and stage two of photosynthesis?
 Stage 1 – sun’s energy is captured
 Stage 2 – captured light energy, hydrogen, and carbon dioxide are used to produce sugars
(glucose)
46. What does the chlorophyll do during photosynthesis?
 Captures the energy from sunlight
47. What are the reactants and products of photosynthesis?
 Reactants – light energy + carbon dioxide + water
 Products – glucose + oxygen
48. What is the word equation for photosynthesis?
 Light energy + carbon dioxide + water  glucose + oxygen
49. How does photosynthesis benefit heterotrophs?
 Heterotrophs cannot make their own food and therefore depend on the process of
photosynthesis
50. What is cellular respiration?
 The process by which cells obtain energy from glucose
51. What are reactants and products of cellular respiration?
 Reactants – glucose + oxygen
 Products – carbon dioxide + water +energy
52. What is the word equation for cellular respiration?
 glucose + oxygen  carbon dioxide + water +energy
53. What happens during stage one and stage two of cellular respiration?
 In the cytoplasm, glucose is broken down into smaller molecules, releasing a small amount of
energy
 In the mitochondria, the smaller molecules react, producing carbon dioxide, water, and large
amounts of energy.
54. Why is the cycle created by photosynthesis and cellular respiration important?
 The processes rely on one another for survival.
 The processes form a cycle that keeps the levels of oxygen and carbon dioxide fairly constant in
the Earth’s atmosphere
55. What is fermentation?
 An energy releasing process that does not require oxygen
56. What is the difference between aerobic respiration and anaerobic respiration?
 Aerobic requires oxygen
 Anaerobic does not require oxygen
57. What is an example of aerobic respiration?
 Cellular respiration
58. What is an example of anaerobic respiration?
 Fermentation
59. Why do cells divide?
 Growth and repair
60. What is the cell cycle? Know the three stages.
 The regular sequence of growth and division that cells undergo
 Interphase, Mitosis, and Cytokinesis
61. What is replication?
 The process by which a cell makes an exact copy of the DNA in its nucleus
62. What happens during interphase, mitosis, and cytokinesis?
 Interphase – the cell grows, makes a copy of its DNA, and prepares to divide into two cells by
producing structures (organelles)
 Mitosis – one copy of the DNA is distributed into each of the two daughter cells
 Cytokinesis – cell splits into two daughter cells with identical set of chromosomes
63. What are the four stages of mitosis? Know what happens in each stage.
 Prophase – Centrioles are copied. Chromosomes condense. Centrioles move to opposite sides
of the nucleus. Spindle fibers form a bridge between the ends of the cell. Nuclear membrane
breaks down
 Metaphase – Each chromosome attaches to a spindle fiber at its centromere. Chromosomes
line up at the center of the cell
 Anaphase – Centromeres split, pulling the chromatids apart. Chromosomes are drawn by their
spindle fibers to opposite ends of the cell. Cell stretches out.
 Telophase – nuclei are forming, spindle fibers, disappear, cell is pinched around its middle
64. What is meiosis? Why does crossing over occur during meiosis?
 The process by which the number of chromosomes is reduced by half as sex cells form

Genetic variation is necessary for meiosis, so crossing over occurs. This means the parent may
pass on a different gene than is expressed. Mitosis is used for cell duplication, so they want
exact duplicates, therefore no genes are crossed over.
65. What kinds of cells are created during mitosis? Meiosis?
 Mitosis – all of the body cells except sex cells
 Meiosis – only sex cells
66. How are mitosis and meiosis different?
 Number of cell divisions
i. Mitosis – 1
ii. Meiosis – 2
 Number of chromosomes in human cells
i. Mitosis – 46
ii. Meiosis – 23
 Type of reproduction
i. Mitosis – asexual reproduction
ii. Meiosis – sexual reproduction
 Genetic makeup
i. Mitosis – genetically identical to parent cell
ii. Meiosis – genetically different from parent cell
 Type of cell created
i. Mitosis – all body cells EXCEPT sex cells
ii. Meiosis – sex cells
67. Why is Mendel known as the father of genetics?
 Before Mendel, people thought that the traits of an individual organism were simply a blend of
the parents’ characteristics. Mendel showed that offspring traits are determined by individual,
separate alleles inherited from each parent
68. Study the diagram of Mendel’s experiment. Why didn’t the short trait show up in the F1 generation?
Why were all the plants tall in the F1 generation?
 Short is a recessive trait that was “hidden” by the dominant/tall trait
69. Why was Mendel surprised with the F2 generation?
 He thought that the short trait had been lost, but was simply masked by the tall/dominant trait
70. Why does each gene have two alleles?
 Offspring inherit 2 alleles, 1 from the egg and 1 from the sperm
71. Why is a Punnett square used? Know how to calculate probability using a Punnett square.
72. Punnett squares are used to see the possible ways alleles can combine in a genetic cross to determine
the probability of a particular outcome or result.
73. How are genotypes and phenotypes different?
 Genotypes – an organisms genetic makeup or alleles (ex. Tt)
 Phenotypes – an organism’s PHYSICAL appearance, what it looks like (ex. tall)
74. Know how to determine phenotypes based on heterozygous or homozygous genotypes.
 Homozygous – describes an organism whose genotype consists of two identical alleles for a
trait
 Heterozygous – an organism that has two different alleles
75. Example: T=tall t=short What is the phenotype for an organism with a genotype TT? Tt? tt?
T
t
t Tt
Phenotype = 50% tall, 50% short
tt
Genotype = 50% Tt, 50% tt
t
Tt
tt
76. Know how to
determine genotypes based on heterozygous or
homozygous phenotypes. What is the genotype for an organism that is homozygous tall?
Heterozygous tall? Homozygous short?
 Homozygous tall = TT
 Heterozygous tall = Tt
 Homozygous short = tt
77. What type of patterns of inheritance affect most traits?
 COMPLEX
78. What is incomplete dominance? Know how to complete a Punnett square showing incomplete
dominance.
 Incomplete dominance occurs when one allele is only partially dominant
i. RR – Red plant, WW – white plant/no red color, if your Punnett square results in a RW,
then the flowers will look pink
79. What is the difference between inherited traits and acquired traits?
 Inherited traits are something that you’re born with
 Acquired traits are something that develops over time (ex. a callus on your finger or the
language that someone speaks)
80. Why can’t changes in body cells be passed to offspring?
 Only changes in sex cells can be passed to offspring
81. Where are the genes located?
 Chromosomes
82. How many pairs of chromosomes do humans have?
 23 pairs (46 total)
83. How many chromosomes do sex cells have?
 23
84. What is DNA?
 DNA, deoxyribonucleic acid, is the heredity material in humans and almost all other organisms
85. Why is DNA important?
 Contains all the genetic instruction used in growth, development, functioning and reproduction
of all known living things
86. What is the shape of DNA?
 Double helix or a twisted ladder
87. What determines the information available for building and maintaining an organism?
 DNA
88. What is a mutation?
 Any change in the DNA of a gene or chromosome
89. How are mutations passed to offspring?
 When chromosome don’t separate correctly during the formation of sex cells
90. What are the three types of DNA mutations?
 Substitution
 Addition
 Deletion
91. What are some examples of helpful mutations? What are some examples of harmful mutations?
 Helpful – born very intelligent,
 Harmful – down syndrome, albino alligator that might be more visible to prey
92. What is cancer?

Cancer is a disease in which cells grow and divide uncontrollably, damaging the parts of the
body around them
93. How do scientists think cancer spreads?
 Scientists believe that cancer begins when something damages a portion of the DNA in a
chromosome. Mutations disrupt the normal cell cycle, causing cells to divide in an uncontrolled
way. They form a mass called a tumor. Some cells break off the tumor and get carred by the
blood stream to other parts of the body.