PNB 2250 Exam Questions and
Answers 100% Pass
How are plant cells held together? - ✔✔Plasmodesma
Plasmodesma - ✔✔Flow of nutrients between cells
How are animal cells held together? - ✔✔Tight junctions
Tight junctions - ✔✔Unique connections for animal cells
2 absolute requirements of animals: - ✔✔1. Control Systems
2. Distribution Systems
True/False: gene number is proportional to physical structure or complexity -
✔✔FALSE - it is NOT proportional
Which fossils do we find the most of? - ✔✔Newer, marine animals
Extant ancestor of animals - ✔✔Chaonoflagellates
Examples of convergent evolution - ✔✔- Flight in insects, bats, birds
- Opposable thumbs in opossums
Katelyn Whitman, All Rights Reserved © 2025 1
,- Echolocation in whales, bats, shrews
Why is immortality impossible? - ✔✔The universe does not have an infinite amount of
energy
George Wald - ✔✔Discovered the prevalence of CHONPS - 96% of body mass
4 characteristics of CHONPS - ✔✔- 2 or fewer electron shells
- strong intramolecular bonds
- double and triple bonds
- maintenance of structure
Animals strive to maintain their internal environment suitable for life, or _____ -
✔✔Homeostasis
Claude Bernard - ✔✔discovered homeostasis
Homeostasis - ✔✔A constant internal environment in the face of a changing external
environment
3 examples of components of homeostasis - ✔✔Body temp.
Blood pH
Blood glucose
Components of a feedback loop - ✔✔- Sensor
Katelyn Whitman, All Rights Reserved © 2025 2
, - Variable
- Output
Feedback Loop: sensor - ✔✔A protein based biochemical amplifier
Feedback Loop: Output - ✔✔Change in physiological variable
Most common type of feedback - ✔✔Negative
Negative feedback - ✔✔Reducing the change in physiological variables
In the geological past, there were toxic concentrations of: - ✔✔NH4, CH4, and CO2
Basis of the food chain for all marine life - ✔✔Phytoplankton
How did phytoplankton create Earth's capability for animal life? - ✔✔Converted Earth
from a chemical reducing state to an oxidizing state
When did photosynthesis begin? - ✔✔2.5 BYA
When did animals appear on Earth? - ✔✔1.2 BYA
Cambrian Explosion - ✔✔Once the Earth became more favorable for animal life, there
was a rapid explosion in animal number and diversity
Possible causes of the Cambrian Explosion - ✔✔- Hyperoxia
- Prior massive glaciation
Katelyn Whitman, All Rights Reserved © 2025 3
Answers 100% Pass
How are plant cells held together? - ✔✔Plasmodesma
Plasmodesma - ✔✔Flow of nutrients between cells
How are animal cells held together? - ✔✔Tight junctions
Tight junctions - ✔✔Unique connections for animal cells
2 absolute requirements of animals: - ✔✔1. Control Systems
2. Distribution Systems
True/False: gene number is proportional to physical structure or complexity -
✔✔FALSE - it is NOT proportional
Which fossils do we find the most of? - ✔✔Newer, marine animals
Extant ancestor of animals - ✔✔Chaonoflagellates
Examples of convergent evolution - ✔✔- Flight in insects, bats, birds
- Opposable thumbs in opossums
Katelyn Whitman, All Rights Reserved © 2025 1
,- Echolocation in whales, bats, shrews
Why is immortality impossible? - ✔✔The universe does not have an infinite amount of
energy
George Wald - ✔✔Discovered the prevalence of CHONPS - 96% of body mass
4 characteristics of CHONPS - ✔✔- 2 or fewer electron shells
- strong intramolecular bonds
- double and triple bonds
- maintenance of structure
Animals strive to maintain their internal environment suitable for life, or _____ -
✔✔Homeostasis
Claude Bernard - ✔✔discovered homeostasis
Homeostasis - ✔✔A constant internal environment in the face of a changing external
environment
3 examples of components of homeostasis - ✔✔Body temp.
Blood pH
Blood glucose
Components of a feedback loop - ✔✔- Sensor
Katelyn Whitman, All Rights Reserved © 2025 2
, - Variable
- Output
Feedback Loop: sensor - ✔✔A protein based biochemical amplifier
Feedback Loop: Output - ✔✔Change in physiological variable
Most common type of feedback - ✔✔Negative
Negative feedback - ✔✔Reducing the change in physiological variables
In the geological past, there were toxic concentrations of: - ✔✔NH4, CH4, and CO2
Basis of the food chain for all marine life - ✔✔Phytoplankton
How did phytoplankton create Earth's capability for animal life? - ✔✔Converted Earth
from a chemical reducing state to an oxidizing state
When did photosynthesis begin? - ✔✔2.5 BYA
When did animals appear on Earth? - ✔✔1.2 BYA
Cambrian Explosion - ✔✔Once the Earth became more favorable for animal life, there
was a rapid explosion in animal number and diversity
Possible causes of the Cambrian Explosion - ✔✔- Hyperoxia
- Prior massive glaciation
Katelyn Whitman, All Rights Reserved © 2025 3
