BIOL 1441 LECTURE FINAL EXAM, UTA
2025 QUESTIONS AND ANSWERS
About 25 of the 92 natural elements are known to be essential to life. Which four of these 25
elements make up approximately 96% of living matter? - ANS carbon, hydrogen, nitrogen,
oxygen
Trace elements are those required by an organism in only minute quantities. Which of the
following is a trace element that is required by humans and other vertebrates, but not by other
organisms such as bacteria or plants? - ANS iodine
Which of the following statements is false?
A) Carbon, hydrogen, oxygen, and nitrogen are the most abundant elements of living matter.
B) Some trace elements are very abundant on Earth.
C) Virtually all organisms require the same elements in the same quantities.
D) Iron is an example of an element needed by all organisms.
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,E) Other than some trace elements, animals are mostly made up of the same elements as
plants, in similar proportions. - ANS C) Virtually all organisms require the same elements in
the same quantities.
Why is each element unique and different from other elements in chemical properties? -
ANS Each element has a unique number of protons in its nucleus
Knowing just the atomic mass of an element allows inferences about which of the following? -
ANS the number of protons plus neutrons in the element
In what way are elements in the same column of the periodic table the same? - ANS They
have the same number of electrons in their valence shell.
Oxygen has an atomic number of 8 and a mass number of 16. Thus, what is the atomic mass of
an oxygen atom? - ANS approximately 16 daltons
Carbon-12 is the most common isotope of carbon, and has an atomic mass of 12 daltons. A
mole of carbon in naturally occurring coal, however, weighs slightly more than 12 grams. Why?
- ANS Some carbon atoms in nature have more neutrons.
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,The precise weight of a mole of some pure elements like silicon (Si) can vary slightly from the
standard atomic mass, or even from sample to sample. Why? - ANS The element may have
multiple stable isotopes, and the isotopic composition may vary from sample to sample.
One difference between carbon-12 ( ) is that carbon-14 ( ) has - ANS two more neutrons than
carbon-12.
An atom has 6 electrons in its outer shell. How many unpaired electrons does it have? -
ANS 2
The atomic number of nitrogen is 7. Nitrogen-15 is heavier than nitrogen-14 because the
atomic nucleus of nitrogen-15 contains how many neutrons? - ANS 8
Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient
energy, a possible result is that - ANS an electron may move to an electron shell farther away
from the nucleus.
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, From its atomic number of 15, it is possible to predict that the phosphorus atom has -
ANS 15 protons and 15 electrons.
The atomic number of each atom is given to the left of each of the elements below. Which of
the atoms has the same valence as carbon (12 6 C )? - ANS 14Si silicon
Two atoms appear to have the same mass number. These atoms - ANS must have the same
number of protons + neutrons.
Fluorine has an atomic number of 9 and a mass number of 19. How many electrons are needed
to complete the valence shell of a fluorine atom? - ANS 1
What is the maximum number of electrons in a single 2 p orbital of an atom? - ANS 2
Phosphorus-32, a radioactive isotope of phosphorus-31 (atomic number 15), undergoes a form
of radioactive decay whereby a neutron turns into a proton and emits radiation in the form of
an electron. What is the product of such radioactive decay of phosphorus-32? - ANS sulfur-
32 (atomic number 16)
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2025 QUESTIONS AND ANSWERS
About 25 of the 92 natural elements are known to be essential to life. Which four of these 25
elements make up approximately 96% of living matter? - ANS carbon, hydrogen, nitrogen,
oxygen
Trace elements are those required by an organism in only minute quantities. Which of the
following is a trace element that is required by humans and other vertebrates, but not by other
organisms such as bacteria or plants? - ANS iodine
Which of the following statements is false?
A) Carbon, hydrogen, oxygen, and nitrogen are the most abundant elements of living matter.
B) Some trace elements are very abundant on Earth.
C) Virtually all organisms require the same elements in the same quantities.
D) Iron is an example of an element needed by all organisms.
Copyright ©2025 BRIGHTSTARS ALL RIGHTS RESERVED
1
,E) Other than some trace elements, animals are mostly made up of the same elements as
plants, in similar proportions. - ANS C) Virtually all organisms require the same elements in
the same quantities.
Why is each element unique and different from other elements in chemical properties? -
ANS Each element has a unique number of protons in its nucleus
Knowing just the atomic mass of an element allows inferences about which of the following? -
ANS the number of protons plus neutrons in the element
In what way are elements in the same column of the periodic table the same? - ANS They
have the same number of electrons in their valence shell.
Oxygen has an atomic number of 8 and a mass number of 16. Thus, what is the atomic mass of
an oxygen atom? - ANS approximately 16 daltons
Carbon-12 is the most common isotope of carbon, and has an atomic mass of 12 daltons. A
mole of carbon in naturally occurring coal, however, weighs slightly more than 12 grams. Why?
- ANS Some carbon atoms in nature have more neutrons.
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2
,The precise weight of a mole of some pure elements like silicon (Si) can vary slightly from the
standard atomic mass, or even from sample to sample. Why? - ANS The element may have
multiple stable isotopes, and the isotopic composition may vary from sample to sample.
One difference between carbon-12 ( ) is that carbon-14 ( ) has - ANS two more neutrons than
carbon-12.
An atom has 6 electrons in its outer shell. How many unpaired electrons does it have? -
ANS 2
The atomic number of nitrogen is 7. Nitrogen-15 is heavier than nitrogen-14 because the
atomic nucleus of nitrogen-15 contains how many neutrons? - ANS 8
Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient
energy, a possible result is that - ANS an electron may move to an electron shell farther away
from the nucleus.
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3
, From its atomic number of 15, it is possible to predict that the phosphorus atom has -
ANS 15 protons and 15 electrons.
The atomic number of each atom is given to the left of each of the elements below. Which of
the atoms has the same valence as carbon (12 6 C )? - ANS 14Si silicon
Two atoms appear to have the same mass number. These atoms - ANS must have the same
number of protons + neutrons.
Fluorine has an atomic number of 9 and a mass number of 19. How many electrons are needed
to complete the valence shell of a fluorine atom? - ANS 1
What is the maximum number of electrons in a single 2 p orbital of an atom? - ANS 2
Phosphorus-32, a radioactive isotope of phosphorus-31 (atomic number 15), undergoes a form
of radioactive decay whereby a neutron turns into a proton and emits radiation in the form of
an electron. What is the product of such radioactive decay of phosphorus-32? - ANS sulfur-
32 (atomic number 16)
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4
