Cell Structure and Function, Exams of Biology

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What is matter, and what states can it exist in? - ANSWER>>Matter is anything that takes up space, by having a volume, and has mass. Matter can exist in a solid, liquid or gaseous (vapor) state.

All matter is made up of certain basic substances called elements.

Explain the difference between essential and trace elements. - ANSWER>>Essential elements are required for human life. Trace elements are required only in small quantities.

Match each of the following molecular bonds with the correct description.

Ionic bonds - ANSWER>>Generated based on the attraction between oppositely charged particles.

Match each of the following molecular bonds with the correct description.

Covalent bonds - ANSWER>>Occurs when electrons are shared by two atoms to complete the valence shells of both.

Match each of the following molecular bonds with the correct description.

Hydrogen bonds - ANSWER>>Forms relatively weak bond that is easily broken.

True or False. If false, make the statement true:

Anions are positively charged ions, and cations are negatively charged ions. - ANSWER>>False. Cations are positively charged ions, and anions are negatively charged ions.

Which of the following are not one fo the organic compounds that make up a biomacromolecules?

1. Lipids
2. Proteins
3. Ribosomes
4. Carbohydrates - ANSWER>>Ribosomes.

What are carbohydrates? - ANSWER>>Carbohydrates, commonly referred to as sugars, are the primary source of fuel for organisms and have the same three elements in their main structure: carbon, hydrogen, and oxygen.

This is a biomacromolecule.

Why are lipids unique among the biomacromolecules? - ANSWER>>Lipids are unique among the biomacromolecules because most of them are insoluble in water. Additionally, lipids are not monomers but are assembled from smaller molecules that are chemically linked together.

Why are lipids insoluble in water? - ANSWER>>Lipids are insoluble in water because they are made mostly of non-polar hydrocarbon chains. As water is polar, it will only dissolve other polar or ionically bonded substances. Lipids are non- polar, and this is why they are insoluble in water but can dissolved with non-polar solvents such as alcohol.

Describe the structure of a phospholipid. - ANSWER>>Phospholipids contain two main components: (1) a polar head group joined to (2) a non-polar tail group.

The head is composed of a charged phosphate group and (usually) a nitrogen- containing group. The head is attracted to polar substances, such as water, and is therefore hydrophilic (water loving). The tail group is a hydrocarbon-- a molecule containing an H and C-- composed of non-polar fatty acid chains. The tail repels water and is therefore hydrophobic (water fearing).

Name the functions of proteins as mentioned in the module. (7) - ANSWER>>Proteins

-can act as enzymes and regulate metabolic functions, -store amino acids, -act as hormones, -form antibodies for immunological defense, -act as carriers for transport and also form membrane channels, -form cell surface receptors to receive chemical messages, -act as structural molecules for support and movement.

Describe how the shape of a protein is related to its function. (3) - ANSWER>>Proteins can be assembled into a variety of shapes which allows them to serve a variety of functions. Some functions of proteins are to make many needed protective tissues such as skin, hair, and fingernails. Proteins also form enzymes (catalysts that speed up chemical reactions) and are used to make needed substances such as hemoglobin, which carries oxygen in red blood cells.

What are the roles of the two major types of nucleic acids? - ANSWER>>There are two major types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

DNA contains a vast amount of hereditary information and is responsible for the inheritable characteristics of living organisms.

RNA is responsible for deciphering the hereditary information in DNA and using it to synthesize proteins.

Describe the structure of DNA and RNA. - ANSWER>>DNA and RNA exist as chains of nucleotides. The sugar of one nucleotide is linked to the phosphate of the next nucleotide, while the nitrogenous base protrudes from each sugar in the string.

RNA is most commonly a single chain of nucleotides, whereas DNA is a double chain held together by hydrogen bonds between protruding bases.

What are some of the main differences between prokaryotic and eukaryotic cells?

• ANSWER>>Prokaryotic cells (also-called prokaryotes) are considered simple cells and have three defining characteristics: size, non-enclosed genetic material and lack of organelles and other internal membrane bound structures.

Eukaryotic cells are more complex than prokaryotic cells. Most organisms are composed of eukaryotic cells. Unlike prokaryotes, eukaryotes are 10-100 times larger, possess a nuclear membrane (eukaryotic means "true nucleus") and contain membrane-bound organelles.

What organelles of the cells are complexes of tiny manufacturing plants that assemble proteins?

1. Endoplasmic reticulum
2. Lysosomes
3. Nucleus

4. Ribosomes - ANSWER>>Ribosomes.

What 3 types of protein fibers make up the cytoskeleton? - ANSWER>>The cytoskeleton is made of protein fibers called microtubules, microfilaments, and intermediate filaments.

Which type of cell junctions are mechanical structures that wrap around the cell to prevent extracellular fluid from leaking?

1. Gap junctions
2. Synaptic junctions
3. Tight junctions
4. Desmosomes - ANSWER>>Tight junctions.

What is the purpose of the cell membrane? - ANSWER>>The cell membrane (plasma membrane) is the outermost constituent of the cell. This membrane is responsible for enclosing the cell's cytoplasm and organelles and separates the extracellular (external) environment from the intracellular (internal) cellular environment.

Explain the main difference between passive and active transport and provide an example of each. - ANSWER>>Passive diffusion occurs when substances move through the membrane without the input of energy; whereas, active transport occurs when an input of energy is required to move substances through the membrane.

Ex of passive: In this situation, we will be talking about breathing. When you take oxygen into your lungs, the surrounding area/cells have a higher concentration of CO2. The difference in concentration results in CO2 going into the lungs. Since

there is also a low amount of oxygen in the cells, the oxygen passively goes from the lungs to the cells (hemoglobin). Then the CO2 is release into the air and the process repeats.

--Simple examples of passive: simple diffusion, osmosis, and filtration.--

Ex of active: When there is more sodium in the cell, the cell will actively transport it against the gradient to allow the electrochemical gradient to go back to its normal state.

--Another example of active: the sodium-potassium pump.

Why is the electrochemical gradient important for cellular function? (4) - ANSWER>>The electrical potential of ions across the cell membrane is an important element for nerve conduction, muscle contraction, mitochondrial metabolism, and hormone secretion.

Matter can exist in which of the following states? Select all that apply.

• Gaseous
• Solid
• Catatonic
• Liquid
• Basic - ANSWER>>- Gaseous.
• Solid.

• Liquid.

Fill-in-the-Blank:

The foundational building blocks of proteins are the organic compounds ________, which are held together by ________ bonds. - ANSWER>>Amino acids; peptide.

What does the term selective permeability mean? - ANSWER>>Selective permeability is characterized by the ability of certain substances to pass through the cell membrane while other molecules cannot.

What type of lipid is made up of four, fused carbon rungs with attached functional groups that often contain an alcohol? - ANSWER>>Steroids.

What type of ion carries a positive charge? - ANSWER>>Cations.

Which organelle of the cell contains the genomic content of the cell and serves as the control center of the cell?

1. Lysosomes
2. Golgi apparatus
3. Nucleus
4. Mitochondria - ANSWER>>Nucleus.

Which of the following is/are alternative strategies of transportation used for larger macromolecules such as polysaccharides or proteins? Select all that apply.

• Phagocytosis

• Endocytosis
• Vesicles
• Sodium-potassium pump
• Osmosis
• Pinocytosis - ANSWER>>- Phagocytosis.
• Endocytosis.
• Vesicles.

What are the four main types of organic molecules that make up biomacromolecules? - ANSWER>>Carbohydrates, lipids, proteins, and nucleic acids.

What type of cell junctions are mechanical structures that wrap around the cell to prevent extracellular fluid from leaking? - ANSWER>>Tight junctions.

Nucleic acids are polymers built from monomers called ________.

1. Nucleotides
2. Fatty acids
3. Phospholipids
4. Polysaccharides - ANSWER>>Nucleotides.

True or False; If false, make the statement true.

Most organisms are composed of prokaryotic cells. - ANSWER>>False; Most organisms are composed of eukaryotic cells.

Fill-in-the-Blank:

________ elements are required only in small quantities, whereas, ________ elements are required for human life. - ANSWER>>Trace; essential.

As part of the cytoskeleton, what are the roles of microfilaments? - ANSWER>>Microfilaments are thinner and made of two intertwined protein polymers of actin. These structures provide structural support to the cells shape as well as a means of motility.

What are the two main components of phospholipids? - ANSWER>>(1) A polar head group joined to (2) a non-polar tail group.

Fill-in-the-Blank:

Specific ions bind to ________, and when a certain concentration has successfully attached, the conformation of the channel changes allowing for ions on the outside to passively diffuse into the cell. - ANSWER>>Carrier proteins.

What occurs in a dehydration reaction? - ANSWER>>Dehydration reactions are called so because, intuitively, a water molecule is lost from the reactant side of the chemical equation.

Name TWO of the four types of passive transport. - ANSWER>>There are four types of passive movement: (1) simple diffusion, (2) osmosis, (3) filtration and (4) facilitated diffusion.

Which of the following statements is TRUE regarding prokaryotic cells?

• Prokaryotic cells contain membrane-bound organelles.

• Prokaryotic cells lack a nuclear membrane.
• Prokaryotic cells contain a nucleus that contains the genetic material of the cell.
• Prokaryotic cells are typically larger than eukaryotic cells. - ANSWER>>Prokaryotic cells lack a nuclear membrane.

What model of membrane structure proposes that the membrane is a phospholipid bilayer in which proteins are either partially or entirely embedded? - ANSWER>>The fluid-mosaic model.

Which of the following bonds forms a relatively weak bond that is easily broken?

1. Covalent
2. Polar
3. Ionic
4. Hydrogen - ANSWER>>Hydrogen.

True or False; If false, make the statement true.

The electrical potential of ions across the cell membrane is an important element for nerve conduction, muscle contraction, mitochondrial metabolism, and hormone secretion. - ANSWER>>True.

List THREE functions of proteins. - ANSWER>>Any 3 of the following are acceptable:

(Proteins)

-can act as enzymes and regulate metabolic functions, -store amino acids, -act as hormones, -form antibodies for immunological defense, -act as carriers for transport and also form membrane channels, -form cell surface receptors to receive chemical messages, -act as structural molecules for support and movement.

Fill-in-the-Blank:

________ are simple sugar carbohydrates made up of a single monomer, and ________ are complex sugars, such as glycogen. - ANSWER>>Monosaccharides; polysaccharides.

Explain what happens to a cell when it is placed in a hypotonic solution. - ANSWER>>When placed in a hypotonic solution, the cell will see an influx of water and will swell in size. Water flows inward to dilate the internal solute concentration (which is higher than the external solution) and obtain equilibrium. However, when the solute concentration is significantly lower than the internal cellular solute concentration, the high volume of water movement will often cause the cell to not only swell but possibly even burst.

Which of the following nitrogenous bases can be found in DNA? Select all that apply.

• Cytosine
• Adenine
• Uracil
• Guanine

• Thymine - ANSWER>>- Cytosine.
• Adenine.
• Guanine.
• Thymine.

The broadest level of biological organization, capable of sustaining life best describes a(n):

1. Biosphere.
2. Ecosystem.
3. Community.
4. Population.
5. Organsim. - ANSWER>>Biosphere.

Each of the following are true regarding Eukaryotes except:

1. They are larger and generally more complex than Prokaryotes.
2. Their nucleus is not membrane bound.
3. Their cell walls do not contain peptidoglycan.
4. They can be divided into 4 main kingdoms: Fungi, Protista, Plantae, Animalia. - ANSWER>>Their nucleus is not membrane bound.

True or False. If false, explain why it is false.

The mRNA found in cells of the archaea domain would be identical to those found in the eubacteria domain. - ANSWER>>False.

Ribsomonal RNA is unique to the organism. This is why a lot of scientist study rRNA to find out information about the organism. The rRNA can be different due to multiple reasons. It allows one to make ribosomes and synthesize proteins.

Fill in the blank:

___________ plants have cells joined into tube like structures that allow for the transport of water and nutrients throughout the plant body. - ANSWER>>Vascular.

Blight attacks which of the following Eukaryotic kingdoms?

1. Fungi
2. Protista
3. Plantae
4. Animalia - ANSWER>>Plantae.

Explain how the cell, the most basic unit of life, can depict the characteristic of life, order. - ANSWER>>The cell is itself highly ordered as it contains organelles, a dedicated cytoplasmic space, conducts metabolic processes, and undergoes microscale adaptions.

Fill in the blank:

Prokaryotes, known as ___________, break down dead and dying organisms and release vital elements such as carbon, nitrogen, and phosphorous into the environment. - ANSWER>>Detritivores or Decomposers.

Which of the following is/are true of the Eukaryotic kingdom, Animalia? (select all that apply)

-All members of this kingdom are considered "consumers".

-All organisms are multicellular and heterotrophic.

-Organisms may be unicellular or multicellular.

• Organisms are multicellular and autotrophic. - ANSWER>>-All members of this kingdom are considered "consumers".

-All organisms are multicellular and heterotrophic.

Fill in the blank:

In the Linnaean classification system, the largest and broadest category, which encompasses all the other taxa, is the ___________. - ANSWER>>Domain.

Each of the following is true regarding the Monera Kingdom except:

1. It is not recognized by all scientists as a Kingdom.
2. It contains microscopic organisms that are some of the oldest inhabitants of planet Earth.
3. Plasmodium can be found in this Kingdom.

4. It is meant to collect all Prokaryotic organisms into one Kingdom. - ANSWER>>Plasmodium can be found in this Kingdom.

Give an example of a specific type of extremophile and describe the type of environment it would live in. - ANSWER>>Thermophiles thrive in higher temperatures such as volcanos; halophiles can be found in extremely saline environments such as the Dead Sea, and psychrophiles which thrive in arctic temperatures such as the tundra of Antarctica.

Which of the following is considered a "secondary consumer"?

1. Autotrophs
2. Herbivores
3. Carnivores
4. Detritivores - ANSWER>>Carnivores.

___________ reproduction involves the fusion of two ___________ that will unite and grow into a new offspring. - ANSWER>>Sexual; gametes.

Match each of the following terms with the correct description.

1. Radial symmetry
2. Spherical symmetry
3. Eucoelomates
4. Psuedocoelomates

-Humans are examples. -Roundworms are examples. -Starfish are examples.

• Sponges and some coral are examples. - ANSWER>>Radial symmetry- Starfish are examples.

Spherical symmetry- Sponges and some coral are examples.

Eucoelomates- Humans are examples.

Psuedoelomates- Roundworms are examples.

Fill in the blank:

Pathogenic bacteria cause illness through the production of ___________ and ___________. - ANSWER>>exotoxins: endotoxins.

By what process do most protists reproduce? State whether this process is sexual or asexual. - ANSWER>>Protists reproduce by binary fission and this process is asexual reproduction.

Which of the following is/are true regarding a rooted phylogenic tree? (select all that apply).

-It is used to demonstrate evolutionary relationships.

-It has a node that is shared between the leaves on the tree.

-It illustrates levels of relatedness without making a hypothesis about shared ancestry. - ANSWER>>-It is used to demonstrate evolutionary relationships.

-It has a node that is shared between the leaves on the tree.

True or False. If false, explain why it is false.

In protostome development, a radial cleavage occurs in the cell mass. - ANSWER>>False. In protostome development, a spiral cleavage occurs in the cell mass.

OR

In deuterostome development, a radial cleavage occurs in the cell mass.

(A radial cleavage occurs in a deutrostome development. This means it develops like a sunflower. It starts at the center and goes outward; whereas, protostome development is like a candy cane.)

A relationship between two organisms in which 1 organism benefits while the other remains unharmed or unaffected is best describes as:

1. Mutualism
2. Commensalism
3. Parasitism - ANSWER>>Commensalism.

Each of the following is true of Eubacteria except:

1. Their cellular structure is prokaryotic.
2. Their DNA is found on plasmids.
3. They reproduce by binary fission.
4. Their cell wall does not contain peptidoglycan. - ANSWER>>Their cell wall does not contain peptidoglycan.

Fill in the blank:

Gram ___________ bacteria have a ___________ layer of peptidoglycan in their cell wall. - ANSWER>>Positive; thick.

Explain why a researcher would choose to study a bacterium instead of a human when researching human disease. - ANSWER>>Researchers most likely choose to study bacterium due to these guidelines:

-They are easy to maintain. -Their size is more convenient and smaller. -They are inexpensive. -They can be genetically modified. -They have a short life span. -The research can bring economic and important information.

Other reasons are due to researchers being able to control all/most of the variables of bacteria; whereas, with humans, there are many variables that can't be controlled.

(Humans are incredibly complex, multicellular organisms, and controlling variables can be impossible. More importantly, some experiments are simply not ethical and could potentially harm a human being. Thus, simpler organisms that do not pose serious ethical risks are preferred in biological research).

True or False. If false, explain why it is false.

Organisms found in the Archaea domain house their genetic material in a membrane bound nucleus. - ANSWER>>False. Organisms found in the Archaea domain house their genetic material in structures called plasmids.

Which of the following cycles is maintained through plant photosynthesis and cellular respiration of consumers?

1. Nitrogen
2. Carbon
3. Phosphorus
4. Water - ANSWER>>Carbon.

The thoracic cavity of Eucoelomates houses which organs/structures? - ANSWER>>The heart and lungs.

List the 7 most widely accepted characteristics of living organisms. - ANSWER>>1. Order.

2. Evolutionary adaptation.
3. Regulation.
4. Energy processing.
5. Growth and development.
6. Response to the environment.
7. Reproduction.

Describe evolutionary adaptation and give an example. - ANSWER>>Evolutionary adaptation, often called generational evolution, specifically refers to smaller, genetic changes that allow for better survival of an organism.

For instance, consider camouflage. Animals that are properly camouflaged within their given environment will, theoretically, survive longer and can thus reproduce more. Coat (such as fur) color genes with the greatest survival rate will be strengthened and amplified within the population. Over time, more and more animals will inherit these colors until most of the population has the adaptive camouflage that allows for optimum survival.

What is an adaptation? What characteristic of life would an adaptation fall into? - ANSWER>>An adaptation is a change or a process that allows an organism to become better suited for their environment. They can be physical or behavioral.

For example, a crab's hard shell is a physical adaptation, while a squirrel hibernating through the winter is a behavioral adaptation. This falls into RESPONSE TO THE ENVIRONMENT.

Compare and contrast sexual and asexual reproduction. - ANSWER>>Sexual reproduction involves the fusion of two gametes (one from each parent) that will unite and grow into a new offspring.

Asexual reproduction, in contrast, gives rise to new offspring from a single organism.

A group of one particular species living within defined boundaries of a community best describes a(n):

1. Biosphere
2. Ecosystem
3. Community
4. Population
5. Organism - ANSWER>>Population.

A system of living and non-living things in a region best describes a(n):

1. Biosphere
2. Ecosystem

3. Community
4. Population
5. Organism - ANSWER>>Ecosystem.

What are the 3 domains that comprise the Linnaean Classification system? - ANSWER>>1. Archaea.

2. Eubacteria.
3. Eukarya.

What is the purpose of a phylogenic tree? - ANSWER>>A phylogenic tree is a branching diagram that shows the relationship between different levels of Linnaean classification taxa. Phylogenic trees provide a visual representation of dichotomies concerning evolutionary relationships and enables scientists to unite phylogeny with the classic Linnaean classification systems. Each branch point represents where the two organisms likely share a common ancestor.

(This allows individuals to study the connections of one species compared to one and how they evolved. This is mainly the study of species using their placement on the tree.

True or False.

Extremophiles are a small sub-set of the Archaea domain that live in extreme environments. - ANSWER>>True.

Bacteria that neither benefits from nor harms it host and are often part of the human flora are considered:

1. Commensal

2. Pathogenic - ANSWER>>Commensal.

Bacteria that cause illness are considered:

1. Commensal
2. Pathogenic - ANSWER>>Pathogenic.

Describe what an exotoxin is and give an example. - ANSWER>>Exotoxins are proteins that are secreted by the bacterial cell.

Vibrio cholera is an example.

(An exotoxin is a toxin that occurs outside of the bacterial cell. An example would be a bacteria releasing a toxin that causes the intestinal cells to release chloride ions leading to dehydration.)

Describe what an endotoxin is and give an example. - ANSWER>>Endotoxins are present inside the cell or can be the lipopolysaccharide components of the outer membrane of some bacteria (Gram-negative). Importantly, these toxins are only released upon the death of the bacterial cell when the cell wall begins to decompose.

Salmonella is an example.

(An endotoxin is a toxin that is released inside the bacterial cell. When the cell dies, this is released to the outside surroundings. This is common in Salmonella.)

Describe what a symbiotic relationship looks like between two organisms. - ANSWER>>A symbiotic relationship is a long-term relationship between two organisms in which one or both organisms benefit from the paired interaction.

An example of this would be a commensalism relationship where the bacteria on our skin feed off the oil we release.

What are the 4 main Eukaryote Kingdoms? - ANSWER>>1. Fungi.

2. Protista.
3. Plantae.
4. Animalia.

Describe the process of binary fission and state whether it is a form of sexual or asexual reproduction. - ANSWER>>Binary fission is the process of reproduction where the parent body is seemingly pinched into two halves, resulting in two daughter organisms each with its own nuclei.

This is an example of asexual reproduction.

Compare and contrast 3 types of symmetry found in animal body plans. - ANSWER>>Spherical symmetry: the body of an organism can be visualized as similar halves if any plane passes through the center. Sponges and some coral have spherical symmetry. Animals with this type of symmetry are spherical in shape.

Radial symmetry: an organism's body can be visualized as equal halves when a plane is passed from top to bottom and through the center. Sponges, jellyfish, and starfish exhibit radial symmetry.

Bilateral symmetry can be visualized as one plane dividing an organism's body into two equal halves. Most invertebrates, such as worms, clams, snails, and all vertebrates exhibit bilateral symmetry. Bilateral symmetry can be thought of as left and right, lateral sides; however, passing a plane in other directions allows for scientists to classify animals based on anatomical body planes.

Autotrophs are considered "primary producers". What does this mean? - ANSWER>>They support all other trophic levels.

(They produce the energy themselves; therefore, supplying to other organisms that can not produce or make energy by themselves.)

Herbivores are considered "primary consumers". What does this mean? - ANSWER>>They eat the primary producers.

(They consume the primary producers; therefore, they are the primary consumers. They receive the most energy out of consumption since they directly eat the main source; whereas, carnivores receive less energy out of consumption because its passing through several sources.)

You are considering a model system for research purposes. What are 6 guidelines you should consider for this system. - ANSWER>>1. Easy to maintain.

2. Physical size should be convenient.
3. Inexpensive.
4. Short life cycles.
5. Can be genetically manipulated.
6. Can be used to deliver economically important results.

Which type of chemical reaction is used to join monomers in order to form polysaccharides and involves the loss of only water molecules.

1. Hydrolysis
2. Dehydration
3. Redox
4. Dehydration condensation - ANSWER>>Dehydration.

Describe the differences between anabolism and catabolism. - ANSWER>>Anabolism is the sum of all the synthetic energy- requiring biochemical reactions. Energy is needed for this.

Catabolism is the sum of all the energy- releasing biochemical reactions. Energy is release during this.

Compare and contrast aerobic and anaerobic respiration. - ANSWER>>Aerobic respiration is respiration that creates ATP using oxygen. This releases and create more output of ATP.

Anaerobic respiration is respiration that doesn't require oxygen to create ATP. It uses other molecules such as sulfate.

(Aerobic respiration involves the consumption of oxygen, while anaerobic respiration can proceed in the absence of oxygen. Aerobic respiration yields the greatest amount of ATP and is the primary metabolic process used in the human body.)

What are the three distinct processes of cellular respiration? Where do each occur in the cell? - ANSWER>>Glycolysis, Citric Acid Cycle, and Electron Transport Chain.

Glycolysis occurs in the cytoplasm; whereas, the Citric Acid Cycle and the Electron Transport Chain takes place in the mitochondria.

Describe the products of each of the two main phases of glycolysis. - ANSWER>>The first phase is known as the energy investment phases because two ATP molecules are used (recall the intent is to be making ATP, not using it) to split one glucose molecule into two intermediary molecules or glyceraldehyde 3- phosphate (G3P).