NLN NEX - SCIENCE QUESTIONS & ANSWERS
2025
1. Describe the key difference between organic and inorganic compounds
as illustrated by the example of HCl.
Organic compounds are always liquids, while inorganic
compounds can be solids or gases.
Organic compounds are synthesized in laboratories, while
inorganic compounds are found in nature.
Organic compounds are always larger molecules than inorganic
compounds.
Organic compounds contain carbon and are typically associated
with living organisms, while inorganic compounds do not
primarily consist of carbon, as seen in HCl.
2. Describe how to calculate the H+ concentration from a given pH value.
To calculate the H+ concentration, multiply the pH by 10.
To calculate the H+ concentration, add 10 to the pH value.
To calculate the H+ concentration, use the formula H+
concentration = pH/10.
To calculate the H+ concentration, use the formula H+
concentration = 10^-pH.
3. Organisms must have variation within a population in order for natural
selection to occur. Which situation is an example of this variation?
Some rabbits living in a forest have short, spotted ears, while
,others have long white ears.
A snake living in a desert produces more offspring than other
snakes in the same population.
, A frog living in a pond is eaten by a predator, while others in the
same population survive.
Some birds living in a grassland eat less than other birds who eat
the same food.
4. Describe how the presence of a recessive gene can lead to the survival
challenges of albino corn seedlings.
Albino corn seedlings are more resistant to environmental
stressors than normal seedlings.
Albino corn seedlings grow faster than normal seedlings, leading
to competition for resources.
Albino corn seedlings lack chlorophyll, which prevents them
from photosynthesizing and ultimately leads to their inability to
survive.
Albino corn seedlings have excess chlorophyll, which makes them
more susceptible to disease.
5. Identify the direction of blood flow through the adult heart in the correct
sequence of chambers and vessels. Right Atrium = RA, Left Atrium = LA,
Right Ventricle = RV, Left Ventricle = LV
RA → LA → LV → systemic
LA → LV → pulmonary → RA → RV → systemic
RA → RV → pulmonary → LA → LV → systemic
RA → LV → pulmonary → LA → RV → systemic
6. Describe what an emulsion is and provide an example from the options
given.
An emulsion is a mixture of two immiscible liquids where one is
dispersed in the other, such as mayonnaise.
, An emulsion is a gas dissolved in a liquid, such as carbonated
water.
An emulsion is a solid mixture, like copper sulfate.
An emulsion is a solution of a solid in a liquid, like salt water.
7. A substance that can't be chemically broken down into simpler
substances is considered
A compound.
An electron.
A heterogenous mixture.
A homogenous mixture.
An element.
8. Which type of microscope is specifically used to observe the
endoplasmic reticulum in a cell?
a compound microscope
an electron microscope
a light microscope
a scanning tunneling microscope
9. Digestion in humans and earthworms:
is similar in that in both organisms, digestion is an intracellular
process, occurring in an incomplete digestive system.
is different in that earthworms have a sac plan body plan and
humans have a tube-within-a-tube body plan.
is similar in that in both organisms, digestion occurs in a simple
tract, in which all parts of the tract are similar.
2025
1. Describe the key difference between organic and inorganic compounds
as illustrated by the example of HCl.
Organic compounds are always liquids, while inorganic
compounds can be solids or gases.
Organic compounds are synthesized in laboratories, while
inorganic compounds are found in nature.
Organic compounds are always larger molecules than inorganic
compounds.
Organic compounds contain carbon and are typically associated
with living organisms, while inorganic compounds do not
primarily consist of carbon, as seen in HCl.
2. Describe how to calculate the H+ concentration from a given pH value.
To calculate the H+ concentration, multiply the pH by 10.
To calculate the H+ concentration, add 10 to the pH value.
To calculate the H+ concentration, use the formula H+
concentration = pH/10.
To calculate the H+ concentration, use the formula H+
concentration = 10^-pH.
3. Organisms must have variation within a population in order for natural
selection to occur. Which situation is an example of this variation?
Some rabbits living in a forest have short, spotted ears, while
,others have long white ears.
A snake living in a desert produces more offspring than other
snakes in the same population.
, A frog living in a pond is eaten by a predator, while others in the
same population survive.
Some birds living in a grassland eat less than other birds who eat
the same food.
4. Describe how the presence of a recessive gene can lead to the survival
challenges of albino corn seedlings.
Albino corn seedlings are more resistant to environmental
stressors than normal seedlings.
Albino corn seedlings grow faster than normal seedlings, leading
to competition for resources.
Albino corn seedlings lack chlorophyll, which prevents them
from photosynthesizing and ultimately leads to their inability to
survive.
Albino corn seedlings have excess chlorophyll, which makes them
more susceptible to disease.
5. Identify the direction of blood flow through the adult heart in the correct
sequence of chambers and vessels. Right Atrium = RA, Left Atrium = LA,
Right Ventricle = RV, Left Ventricle = LV
RA → LA → LV → systemic
LA → LV → pulmonary → RA → RV → systemic
RA → RV → pulmonary → LA → LV → systemic
RA → LV → pulmonary → LA → RV → systemic
6. Describe what an emulsion is and provide an example from the options
given.
An emulsion is a mixture of two immiscible liquids where one is
dispersed in the other, such as mayonnaise.
, An emulsion is a gas dissolved in a liquid, such as carbonated
water.
An emulsion is a solid mixture, like copper sulfate.
An emulsion is a solution of a solid in a liquid, like salt water.
7. A substance that can't be chemically broken down into simpler
substances is considered
A compound.
An electron.
A heterogenous mixture.
A homogenous mixture.
An element.
8. Which type of microscope is specifically used to observe the
endoplasmic reticulum in a cell?
a compound microscope
an electron microscope
a light microscope
a scanning tunneling microscope
9. Digestion in humans and earthworms:
is similar in that in both organisms, digestion is an intracellular
process, occurring in an incomplete digestive system.
is different in that earthworms have a sac plan body plan and
humans have a tube-within-a-tube body plan.
is similar in that in both organisms, digestion occurs in a simple
tract, in which all parts of the tract are similar.
