BARB UGA BIO 1108 EXAM 1
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS
What is the basic chemical and physical composition of a plant? ✔✔ Plants
typically consist of 50–75% water, while the remaining 25–50% is dry
biomass. This biomass is primarily composed of carbon (~50%), oxygen
(~42%), and hydrogen (~7%), largely found within cellulose and lignin.
Which elements are considered structural, and how does a plant obtain them? ✔✔
Carbon, hydrogen, and oxygen are the primary structural elements. Plants
extract carbon from the atmosphere, while hydrogen and oxygen are
absorbed from soil water.
Why is carbon specifically vital to plant structure? ✔✔ Carbon acts as the
fundamental building block for essential biomolecules, creating the
"backbone" for starches, proteins, and other critical tissues.
What roles do nitrogen and phosphorus play as primary nutrients? ✔✔ Both are
essential components of DNA, RNA, and ATP. Additionally, phosphorus is a
key ingredient in phospholipids, which are vital for the integrity and
operation of cell membranes.
How does potassium contribute to a plant's physical form? ✔✔ Potassium is
crucial for regulating turgor pressure, which keeps cells rigid and allows the
plant to maintain its upright shape.
Why do plants need nitrogen? -ANSWER✔✔DNA- nitrogenous bases: adenine,
guanine, cytosine, thymine
ATP
, Chlorophyll (captures light energy in photosynthesis)
Amino acids (AA)/proteins
How do most plants obtain nitrogen? (with the assistance of free-living bacteria in
the soil) -ANSWER✔✔nitrogen fixation, nitrification, assimilation
nitrogen fixation -ANSWER✔✔the process by which atmospheric nitrogen gas is
converted to ammonia by free-living N-fixing bacteria in the soil. This ammonia
(NH3) mixes with water in the soil and becomes ammonium (NH4+).
Nitrification -ANSWER✔✔the process by which free-living nitrifying bacteria
living in the soil convert ammonium (NH4+) to nitrites (NO2-, 2 oxygens) which
are then converted by different free-living bacteria in the soil to nitrates (NO3-, 3
oxygens).
Assimilation -ANSWER✔✔the process by which plants take up nitrates (NO3-)
from the soil through their roots via nitrate transporters. Plants can also take up
ammonium (NH4+) through ammonium transporters
How do legumes obtain nitrogen? -ANSWER✔✔With the assistance of symbiotic
bacteria living in nodules in their roots
With the assistance of free-living bacteria in the soil
With the assistance of symbiotic bacteria living in nodules in their roots method -
ANSWER✔✔1. Nitrogen fixation: the process by which atmospheric nitrogen gas
(N2) is converted to ammonia (NH3) by nitrogen-fixing symbiotic bacteria living
in nodules on the roots of the plant, the ammonia (NH3) then mixes with water to
form NH4+ ammonia
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS
What is the basic chemical and physical composition of a plant? ✔✔ Plants
typically consist of 50–75% water, while the remaining 25–50% is dry
biomass. This biomass is primarily composed of carbon (~50%), oxygen
(~42%), and hydrogen (~7%), largely found within cellulose and lignin.
Which elements are considered structural, and how does a plant obtain them? ✔✔
Carbon, hydrogen, and oxygen are the primary structural elements. Plants
extract carbon from the atmosphere, while hydrogen and oxygen are
absorbed from soil water.
Why is carbon specifically vital to plant structure? ✔✔ Carbon acts as the
fundamental building block for essential biomolecules, creating the
"backbone" for starches, proteins, and other critical tissues.
What roles do nitrogen and phosphorus play as primary nutrients? ✔✔ Both are
essential components of DNA, RNA, and ATP. Additionally, phosphorus is a
key ingredient in phospholipids, which are vital for the integrity and
operation of cell membranes.
How does potassium contribute to a plant's physical form? ✔✔ Potassium is
crucial for regulating turgor pressure, which keeps cells rigid and allows the
plant to maintain its upright shape.
Why do plants need nitrogen? -ANSWER✔✔DNA- nitrogenous bases: adenine,
guanine, cytosine, thymine
ATP
, Chlorophyll (captures light energy in photosynthesis)
Amino acids (AA)/proteins
How do most plants obtain nitrogen? (with the assistance of free-living bacteria in
the soil) -ANSWER✔✔nitrogen fixation, nitrification, assimilation
nitrogen fixation -ANSWER✔✔the process by which atmospheric nitrogen gas is
converted to ammonia by free-living N-fixing bacteria in the soil. This ammonia
(NH3) mixes with water in the soil and becomes ammonium (NH4+).
Nitrification -ANSWER✔✔the process by which free-living nitrifying bacteria
living in the soil convert ammonium (NH4+) to nitrites (NO2-, 2 oxygens) which
are then converted by different free-living bacteria in the soil to nitrates (NO3-, 3
oxygens).
Assimilation -ANSWER✔✔the process by which plants take up nitrates (NO3-)
from the soil through their roots via nitrate transporters. Plants can also take up
ammonium (NH4+) through ammonium transporters
How do legumes obtain nitrogen? -ANSWER✔✔With the assistance of symbiotic
bacteria living in nodules in their roots
With the assistance of free-living bacteria in the soil
With the assistance of symbiotic bacteria living in nodules in their roots method -
ANSWER✔✔1. Nitrogen fixation: the process by which atmospheric nitrogen gas
(N2) is converted to ammonia (NH3) by nitrogen-fixing symbiotic bacteria living
in nodules on the roots of the plant, the ammonia (NH3) then mixes with water to
form NH4+ ammonia
