Summative Test 2025 Flashcards
What is an organelle?
Subcellular structures inside cells that perform various jobs/roles.
What are the two categories of cells?
Prokaryotic and eukaryotic
What is an eukaryotic cell?
A cell that makes up single or unicellular organisms, has a nucleus and evolved from prokaryotic cells. Their organelles are membrane-bound.
What is a prokaryotic cell?
Smaller, basic cells that form unicellular protists. They are the oldest types of cell.
What is the cell theory & it’s four parts?
A scientific theory that states: All living things are made of cells, cells are the basic unit of life, cells come from pre-existing cells, and cells contain DNA.
Name the kingdoms that are eukaryotic
Protists (unicellular non-bacteria), animals, plants, fungi
Name the kingdoms that are prokaryotic
Monera (bacteria), all unicellular
What are some features/organelles of prokaryotic cells?
Cell wall, cell membrane, cytoplasm, capsule, flagella, pili
Simple organelles: ribosomes, nucleoid
What do prokaryotic cells lack?
Membrane-bound organelles (mbo), nucleus
Where is DNA located in prokaryotic cells?
Nucleoid
What do prokaryotic & eukaryotic cells have in common?
Both have DNA, Ribosomes, cytoplasm, and cell membrane
Where is DNA located in eukaryotic cells?
Nucleus
What is unique about eukaryotic organelles?
They are membrane-bound
What is a cell wall?
Outer layer of cell that strengthens and helps cell maintain shape. Located only in plant cells and prokaryotic cells.
What are ribosomes and what do they do?
Organelle responsible for producing proteins/protein synthesis. Made of rRNA.
Where are ribosomes found?
Either floating in the cytoplasm or attached to the rough ER.
What is the cytoplasm & it’s role?
Gel-like fluid inside of a cell. It is not an organelle, rather it is the fluid that holds them. Hold and protect organelles, stores organic molecules for cellular processes.
What is the nucleus & it’s role?
MBO found in the cytoplasm of plant and animal eukaryotic cells Enclosed by the nuclear envelope, it houses DNA and controls cellular activities.
What is a nucleoid & it’s role?
A nuclear region found in prokaryotic cells. It is irregularly shaped and holds the DNA of the cell
What are pili & their role?
Hair-like appendages that extend from the body of a cell to aid attachment.
What is the flagella & it’s role?
Hair-like tail that extends from bacteria and sperm cells etc. to help movement.
What is the smooth endoplasmic reticulum & it’s role?
Makes organic (carbon-containing) molecules. The smooth ER makes lipids/fats. Found in animal and plant eukaryotes.
What is the rough endoplasmic reticulum & it’s role?
Makes organic (carbon-containing) molecules. The rough ER makes proteins. Found in animal and plant eukaryotes.
What is mitochondria & their role?
Rod-like MBO found in animal and plant eukaryotic cells
Performs aerobic respiration to make energy available for the cell by producing ATP (an energy-carrying molecule). ATP is broken down to release energy for processes that require energy e.g., active transport of materials into a cell).
What are small temporary vacuoles (vesicles) & their role?
MBO found in animal and plant eukaryotic cells
Carries molecules (e.g., proteins) from the Golgi body to the cell membrane to be released out of the cell (secretion).
What is a lysosome & it’s role?
MBO found only in animal eukaryotic cells
Breaks down damaged organelles.
Helps to digest large food molecules taken into the cell.
What is the golgi body & it’s role?
MBO found in the membrane of animal and plant eukaryotic cells
Packages molecules made by the cell (e.g., proteins) into small temporary vacuoles for transport
What membrane-bound organelles are located in the cytoplasm? (eukaryotic)
Nucleus
Mitochondria
Rough ER
Smooth ER
Golgi Body
Lysosomes (A)
Vesicles
Vacuoles (P)
Chloroplasts (P)
What are large permanent vacuoles & their role?
MBO found only in plant eukaryotic cells
Takes up most of the cell
Stores water/dissolved solutes and helps to maintain cell shape.
What is the chloroplast & its role?
MBO found only in the cytoplasm plant eukaryotic cells containing chlorophyll
Carries out photosynthesis to produce sugars e.g., glucose.
Enables plant cells to obtain energy from the environment.
What is the cell membrane?
A selectively permeable membrane that separates the interior of a cell from the outside environment, acting as a selective barrier that regulates the passage of materials in and out. Its flexible barrier protects the cell, contains its contents, and controls movement in and out.
Describe the structure of the CM
Structure is a phospholipid bi-layer with hydrophilic phosphate heads facing outwards and hydrophobic lipid tais facing inwards
What are phospholipids?
A type of lipid molecule essential to the structure of the cell membrane. They consist of a hydrophilic phosphate head and a hydrophobic lipid tail.
What is selectively permeable and why is it important for the CM?
Selectively permeable means it only lets certain things in and/or out of the CM. This allows it to diffuse materials but maintain structure and internal cell environment.
How does the phospholipid bi-layer form?
As phosphate heads are hydrophilic, they face outwards. Lipid tails are hydrophobic & repel water, so they face in.
What are integral membrane proteins?
Embedded membrane proteins that extend part-way or fully across the CM.
What are peripheral membrane proteins?
Membrane proteins found on the outside of the CM. They are soluble and adhere temporarily.
What are glycoproteins?
Embedded membrane proteins with a carbohydrate chain attached
What are glycolypids?
Phospholipids with a carbohydrate chain attached
Where is cholesterol located on the CM & its purpose?
On the surface of the CM
How does the CM maintain stability?
The hydrophilic pull of phosphate heads outwards and the hydrophobic attraction of lipids creates a strong structure
What is the structure of the CM called?
Fluid mosaic model, phospholipid bi-layer
What are carbohydrate chains?
Chains of carbohydrate molecules found on the cell membrane. Can be attached to phospholipids (glycolipids) or proteins (glycoproteins).
What are channel proteins?
Integral proteins responsible for diffusing materials, typically larger molecules and water.
What are carrier proteins?
Integral proteins that move materials across the CM through pumping.
What is simple diffusion?
Passive diffusion is diffusion of small molecules (carbon, oxygen etc.) through the cell membrane from high to low-concentration gradients. The tightly packed phospholipids allow small molecules to pass through whilst larger molecules cannot.
What are factors that affect diffusion?
Increased temperature, sa: v, agitation, and shallower concentration gradient
What is facilitated diffusion and how does it work?
Passive movement of hydrophilic molecules (eg. glucose) and atoms with a charge (ions like Na+).
As the CM is mostly hydrophobic, channel proteins allow hydrophilic molecules to pass through facilitated diffusion.
Moves with the concentration gradient
What is osmosis and how does it work?
Osmosis is a type of passive movement of water molecules across the cell membrane from high to low concentrations.
Water molecules are small enough to diffuse between phospholipids. Specific channel proteins (aquaporins) provide a path for water molecules only to pass, speeding up diffusion.
What is binary fission?
Cell division that occurs in prokaryotes and some single-cellular eukaryotes.
It is a form of asexual reproduction.
When does diffusion occur/stop?
When equilibrium is reached ie. the concentration of molecules outside & inside of the cell is the same.
When does cell division occur?
When the SA: V is too high and the cell is no longer efficient at diffusion
What occurs before binary fission?
DNA is replicated inside the cell.
First step of binary fission
Cytoplasmic membrane/area elongates, separating the DNA. Simultaneously, DNA attaches to CM.
Second step of binary fission
Cell walls grow inwards (furrows) and “pinches” cells. The growth that separates the cells is called the septum.
Third step of binary fission
Cell fully divides as septum closes
Fourth step of binary fission
2 daughter cells, identical to the parent cell, form. Called cloning.
What are the offspring cell of parent cells called?
Daughter cells
What is the acronym for mitosis?
IPMAT+C
What is mitosis?
A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus. Reproduction, repair, and growth
Why is mitosis important?
Without it, dead cells would never be replaced, organisms would never grow or heal.
What is interphase?
Pre-mitosis where DNA replication occurs
What is early prophase?
Prophase prepares the cell for division. Parent cell begins to break the nucleus down, chromosomes become visible and organised
What is late prophase?
Spindle fibres attach to the chromosomes at the centromere
Describe metaphase
Chromosomes line up in the middle of the cell to allow them to separate to opposite ends of the cell. Chromatids prepare to be broken apart.
Describe anaphase
Sister chromatids (previously a chromosome) separate due to spindle fibres pulling them apart. Chromatids are separated to opposite ends of the cell.
Describe telophase
CELL IS NOT COMPLETELY SEPARATED
Daughter cells that are formed begin to separate. Nucleus reforms in each cell around DNA and centrioles disappear
Describe cytokinesis
Daughter cells split completely.
How is the DNA organised in prokaryotic cells?
Single, circular chromosomes
How is the DNA organised in eukaryotic cells?
Multiple, linear chromosomes.
Define a centromere
Centre of a chromosome. Part of the chromosome where spindle fibres attach
What are chromosomes?
An X structure is made of DNA. They allow DNA to be accurately replicated.
Define a chromatid
The single strand of a chromosome
What is a centriole?
Organisms inside a cell that aid organisation of chroms during mitosis
What is the name given to daughter cells of mitosis?
Diploid cells
What is an organic molecule?
Large, complex, carbon-containing molecules essential for a cell’s function
Controls cells activities
eg. DNA, carbohydrate, protein, lipids, fats
What is an autotroph?
Can make organic molecules independently
Usually with chemical reactions (like photosynthesis)
Commonly plants like trees, shrubs grasses
What is a heterotroph?
Those that cannot make organic molecules independently. Must source molecules otherwise eg. though food.
Commonly humans and animals
What is needed to carry out photosynthesis?
Water and CO2.
light is also needed
Photosynthesis produced what?
Glucose and oxygen
What are inorganic substances?
Molecules that lack carbon eg. ammonia
Some simple carbon molecules eg. Carbon
What other factors (not molecules) are required for photosyntheis?
Chlorophyll and light
What is the source of energy for autotrophs?
Light energy
How do heterotrophs use aerobic respiration to get molecules?
Under aerobic conditions (oxygen environment) heterotrophs perform aerobic respiration (in mitochondria) to obtain energy. In aerobic respiration glucose is broken down with oxygen to produce carbon dioxide and water. Energy stored in glucose is released. Some is ‘captured’ as chemical energy stored in ATP. Breakdown of ATP supplies energy for energy-needing cell processes e.g., active transport, cell division. This means the source of energy for heterotrophs is chemical energy.
Then, they have to breathe out the CO2, as well as some oxygen.
Describe photosynthesis
During photosynthesis light energy is transformed (converted) into chemical energy stored in the chemical bonds of a sugar called glucose (an organic molecule). In chloroplasts, CO2 and water (with light and chlorophyll) produce glucose and oxygen.
What is the aerobic respiration word equation?
glucose + oxygen —> carbon dioxide + water
What is the photosynthesis word equation?
carbon dioxide + water –> glucose + oxygen
What is ATP?
Adenosine triphosphate is an energy-carrying molecule
How do autotrophs obtain chemical energy from photosynthesis?
The energy produced from the glucose made in photosynthesis is then used for aerobic respiration. Glucose is broken down with oxygen to produce carbon dioxide and water and energy stored in glucose is released. Some is ‘captured’ as chemical energy stored in ATP. Breakdown of ATP supplies energy for energy-needing cell processes.
Not available to cell unless its stored in ATP
What is fermentation?
Under anaerobic conditions (no oxygen environment) heterotrophs and autotrophs synthesise ATP by performing an energy-releasing process called fermentation.
State the word equation for alcohol fermentation
Alcohol fermentation glucose –> ethanol + carbon dioxide
State the word equation for lactic acid fermentation
Lactic acid fermentation glucose –> lactic acid
What fermentation do heterotrophs/animal cells perform?
Animal cells (and many bacteria) perform lactic acid fermentation.
What fermentation do autotrophs perform?
Plant cells (and yeast) carry out alcohol fermentation.
When and why does fermentation occur?
- When there is no oxygen
- There is a max level of ATP that can be obtained by aerobic respiration.
What are the 3 requirements of cells?
- need organic molecules
- need energy
- must exchange materials with environments
What are inputs and examples?
Inputs are things that must enter the cell to help it function. Some examples include: Glucose, oxygen, amino acids, water, ions
What are outputs and examples?
Things that must be removed from the cell. Some examples are: CO2, urea, hormones, lactic acid
Why do cells need amino acids?
To produce molecules for producing proteins
Why do cells need oxygen?
For aerobic respiration, which makes ATP
Why do cells need glucose?
For aerobic respiration, which makes ATP
Why do cells need water?
MOST IMPORTANTLY: Water provides a medium in the cytoplasm for chem reactions and dissolving of substances.
Also:
Maintaining Shape & Structure, Chemical Reactions, Temperature Regulation (maintain a stable environment), Energy Production (photosynthesis, cellular respiration)
Why do cells need ions?
Help provide a medium in the cytoplasm for chem reactions and dissolving of substances.
What is the main component of a cytoplasm and why?
Water; allows a medium for certain chemical reactions to occur
Why must cells remove lactic acid?
To prevent its accumulation, which can lead to toxic conditions and disrupt normal cellular function.
Why must cells remove CO2?
To prevent its accumulation, which can lead to toxic conditions and disrupt normal cellular function.
Why must cells remove urea?
Byproducts of protein metabolism; toxic if not eliminated.
Why must cells remove hormones?
To regulate body functions, coordinate communication between organs, and maintain homeostasis.
What is the importance of organic molecules?
Help carry out fundamental chemical processes.
Compare characteristics of living and non-living things
Cellular structure: living things are made up of cells whilst non-living are not
Growth: living grow by cell division or enlargement. non-living do not grow on their own
Reproduction: living can reproduce (sexually or asexually).
non-living cannot reproduce.
Movement: living can move independently whilst non-living cannot
Energy: living require energy to function (e.g., from food or sunlight). Non-living do not require energy.
Describe the similarities in structure of prokaryotes and eukaryotes
Both contain DNA, ribosomes, a cytoplasm, and a cell membrane.
Describe the differences in structure of prokaryotes and eukaryotes
MBO: eukaryotic have whilst prokaryotic lack
Size: euk. big, prok. small
Cell number: prokaryotes make up single cellular organisms whilst eukaryotic can make up single or multi cellular (mostly multi)
Nucleus: euk has a nucleus whilst prok has a nucleoid region
Compare the structure of animal and plant cells.
MBO: Both have a nucleus, mitochondria, rough and smooth ER, a golgi body, small temporary vacuoles.
ONLY Plant cells have large permanent vacuoles and chloroplasts
ONLY animal cells have lysosomes
Describe the structure of the selectively permeable membrane.
A phospholipid bi-layer that has embedded and attached (integral & peripheral) membrane proteins. The layer is comprised of hydrophilic heads facing outward and hydrophobic tails facing inward.
The selective permeability allows for small molecules to pass thru the bilayer via diffusion and other molecules to diffuse through channel or carrier proteins whilst maintaining its shape and protecting the cell. Maintains membrane fluidity by preventing it from becoming too rigid or too permeable.
Describe how substances move passively across the cell membrane with the concentration gradient.
Substances move passively across the cell membrane with the concentration gradient (from high to low concentration) without requiring energy/ATP.
Molecules diffuse until equilibrium is reached.
- Simple Diffusion
Movement of small, non-polar molecules (e.g., O₂, CO₂) directly across the phospholipid bilayer.
Example: Oxygen diffusing into cells for respiration. - Facilitated Diffusion
Movement of larger or polar molecules (e.g., glucose, ions) across the membrane through transport proteins.
Requires channel proteins (for ions) or carrier proteins (for larger molecules).
Example: Glucose enters cells via carrier proteins.
- Osmosis (Diffusion of Water)
Water moves across the membrane.
Water moves from an area of high water concentration (low solute) to low water concentration (high solute) through aquaporins (water channels).
Example: Water moving into plant root cells.
Explain how a cell membrane controls exchanges of materials (passive or active) between a cell and its environment.
The CM controls the exchange of materials through selective permeability.
This allows some materials to diffuse in and not others, and vice versa. The ability to “replenish” materials and remove wastes keeps the cell in homeostasis.
Compare passive and active transport with regard for concentration gradient and energy requirement.
Passive transport requires no ATP. Moves down the concentration gradient (high → low concentration) and doesn’t always involve proteins.
Active transport requires ATP, against the concentration gradient (low → high concentration), and is done with the help of carrier or channel proteins.
Describe and represent binary fission in prokaryotic cells.
Asexual reproduction undertaken by prokaryotic cells for population growth.
- DNA Replication
The single circular chromosome duplicates, creating two identical copies. - Cell Growth
The cell elongates, separating the two DNA copies. - Septum Formation
A new cell wall (septum) begins to form in the middle. - Cell Division
The cell splits into two identical daughter cells. - Daughter Cells
Each new cell has one copy of the original DNA and is genetically identical to the parent cell.
Describe and represent mitotic division in eukaryotic cells.
Mitosis produces two genetically identical daughter cells, ensuring an organism’s growth, repair, and maintenance.
Interphase (Pre-Mitosis)
The cell prepares for division by replicating its DNA and growing.
Prophase
Chromosomes condense and become visible.
The nuclear membrane breaks down.
Spindle fibers begin to form.
Metaphase
Chromosomes align at the center (equatorial plate).
Spindle fibers attach to the centromeres of chromosomes.
Anaphase
Spindle fibers pull sister chromatids apart toward opposite poles.
Telophase
Chromatids reach the poles and decondense into chromatin.
The nuclear membrane reforms around each set of chromosomes.
Cytokinesis (Final Step)
The cytoplasm splits, forming two identical daughter cells.
Compare binary fission with mitotic division.
Mitosis:
Eukaryotes (Animals, Plants, Fungi, Protists), growth, repair, and asexual reproduction, Genetically identical, more complex, involves multiple linear chromosomes
Binary fissions:
Prokaryotes (Bacteria), Asexual reproduction, Genetically identical, simple process, single circular chromosome
Compare the sources of organic molecules and energy for autotrophs and heterotrophs.
Autotrophs make organic molecules independently whilst heterotrophs must consume their own. Autotrophs use light energy to perform photosynthesis whilst heterotrophs get chemical energy from aerobic respiration.
Explain why cells need to exchange materials (inputs)
Materials must be exchanged to maintain homeostasis/constant environment.
Absorb:
Oxygen (O₂): for aerobic respiration, producing ATP
Glucose: for aerobic respiration, producing ATP
Water: chemical reactions and maintaining cell structure
Ions: Crucial for nerve signals, enzyme function, and maintaining osmotic balance.
Explain why cells need to exchange materials and the need for removal of wastes.
Lactic Acid: Prevent accumulation, which leads to toxic conditions and disrupts cell function
CO2: Prevent accumulation, which leads to toxic conditions and disrupts cell function
Urea: Byproduct of protein synthesis; toxic
Hormones: Regulate body functions, coordinate communication
What are the three types of microorganisms?
Protists, bacteria, unicellular fungi
Discuss the effects of factors on bacterial growth.
Temperature (20-45 degrees C growth, 0-4 near zero, 50-100 kills), pH level (ideal 7, 1-3 kill), water (lack of reduces growth near zero), nutrients (Less nutrients = less growth as most are autotrophs), removal of waste (if cannot = dies)
