B1 Ai Flashcards
What are the two main types of cells?
Prokaryotic and Eukaryotic
Prokaryotic cells are smaller and simpler, while eukaryotic cells are complex.
What is the function of the nucleus in a cell?
Contains genetic material that controls what the cell does
The nucleus is a key subcellular structure found in eukaryotic cells.
Where do most chemical reactions happen in an animal cell?
Cytoplasm
The cytoplasm is a gel-like substance where various cellular processes occur.
What controls what goes in and out of the cell?
Cell membrane
The cell membrane is semipermeable and regulates the internal environment of the cell.
Where does most aerobic respiration occur in a cell?
Mitochondria
Mitochondria are known as the powerhouse of the cell.
What is the role of ribosomes in a cell?
Where proteins are made
Ribosomes can be found free in the cytoplasm or attached to the endoplasmic reticulum.
What additional structures do plant cells have that animal cells do not?
Cell wall, permanent vacuole, chloroplasts
These structures contribute to the plant’s rigidity, storage, and ability to perform photosynthesis.
What is the function of chloroplasts?
Where photosynthesis happens
Chloroplasts contain chlorophyll, which captures light energy for photosynthesis.
What do bacterial cells lack compared to eukaryotic cells?
True nucleus
Bacterial cells have a single loop of DNA instead of a true nucleus.
What are plasmids?
Small rings of extra DNA found in bacterial cells
Plasmids can carry genes for antibiotic resistance.
Estimate the area of a mitochondrion that is approximately 10 um by 1 um.
10 um²
Area is calculated using the formula: length x width.
Fill in the blank: All living things are made of _______.
cells
This is a fundamental concept in biology.
True or False: All animal and plant cells are eukaryotic.
True
Eukaryotic cells are characterized by their complex structures.
What is the primary function of the cell wall in plant cells?
Supports and strengthens the cell
The cell wall is made of cellulose.
List three subcellular structures found in animal cells.
- Nucleus
- Cytoplasm
- Mitochondria
These structures play vital roles in cellular functions.
What is the primary function of microscopes?
Microscopes magnify things (make them look bigger)
Microscopes are essential tools in biology for observing small structures.
What has contributed to the development of microscope usage over the years?
Technology and knowledge have improved
This advancement allows for more detailed observations and analyses.
What can light microscopes be used to observe?
Cells and large subcellular structures (like the nucleus)
Light microscopes are the most common type used in biology.
How do electron microscopes differ from light microscopes?
They have higher resolution and higher magnification
Electron microscopes can show smaller structures like ribosomes and plasmids.
What are some structures that can be observed using electron microscopes?
- Ribosomes
- Plasmids
These structures are not visible under light microscopes due to their small size.
When were electron microscopes invented in relation to light microscopes?
Electron microscopes were invented after light microscopes
Their invention allowed for a deeper understanding of subcellular structures.
What is magnification?
How many times bigger the image is than the real thing
Magnification helps in quantifying the enlargement of the observed object.
What is the formula to calculate magnification?
magnification = image size / real size
Image size and real size should have the same units for accuracy.
If the width of a cell is 0.02 mm and its image under a microscope is 8 mm, what is the magnification?
400
Calculation: magnification = 8 mm / 0.02 mm = 400.
What is standard form used for?
Writing very big or very small numbers in a simpler way
Standard form makes it easier to read and compare numerical values.
How do you convert 0.0025 mm into standard form?
2.5 × 10^-3
The decimal point moves 3 places to the right, indicating a negative exponent.
What is the first step in converting a number to standard form?
The first number needs to be between 1 and 10
This ensures the standard form is correctly formatted.
True or False: The power of 10 is positive if the decimal point is moved to the left.
True
Conversely, the power of 10 is negative if the decimal point is moved to the right.
What unit should the image size and real size be in when calculating magnification?
They should have the same units
If the units are not the same, the calculation will not work.
What is the first step in preparing a slide for microscopy?
Add a drop of water to the middle of a clean slide.
What type of tissue is used from the onion for microscopy?
Epidermal tissue.
What is the purpose of adding iodine solution to the slide?
Iodine solution is a stain that makes different parts of a cell easier to see.
What should you avoid when placing the cover slip on the slide?
Avoid getting any air bubbles under it.
What is the first action you take when using a light microscope?
Clip the slide onto the stage.
Which objective lens should you select first when using a microscope?
The objective lens with the lowest magnification.
What is the function of the coarse adjustment knob?
To move the stage up to just below the objective lens.
What should you do after looking down the eyepiece?
Move the stage downwards until the image is roughly in focus.
What is the purpose of the fine adjustment knob?
To get a clear image of what’s on the slide.
Fill in the blank: To get a bigger image, use an objective lens with a _______ magnification.
higher
What tool should you use to draw observations under the microscope?
A pencil with a sharp point.
How should you draw the outlines of the cell features?
Use smooth lines.
What should be avoided in the drawings made from microscope observations?
No shading or colouring in.
What is important to include in your drawing besides the cell features?
A title and a scale.
How should the lines used to label features in the drawing be arranged?
Make sure the lines don’t cross over each other.
What should you write down regarding the microscope observation?
The magnification that it was observed under.
What is the real length measurement mentioned in the drawing instructions?
0.3 mm.
What is the magnification of the drawing stated in the text?
×110.
What is the process by which cells change to become specialised?
Differentiation
Differentiation allows cells to develop different subcellular structures to perform specific functions.
At what stage do most animal cells differentiate?
Early stage of the animal’s life
Most differentiation in animals occurs during early development.
Can plant cells differentiate throughout their life?
Yes
Many plant cells can continue to differentiate for the entire lifespan of the plant.
What are stem cells?
Undifferentiated cells
Stem cells have the potential to differentiate into various cell types.
What is a key feature of sperm cells?
They have a tail to help them swim
Sperm cells are specialised for delivering male DNA to the egg.
What do nerve cells do?
Carry electrical signals around the body
Nerve cells are designed to transmit signals efficiently over distances.
How are muscle cells specialised?
They are long and contain many mitochondria
Muscle cells require energy to contract, which is provided by mitochondria.
What is the function of root hair cells?
Absorb water and minerals
Root hair cells have long ‘hairs’ to increase surface area for absorption.
What do phloem cells transport?
Food
Phloem cells form tubes to transport nutrients throughout the plant.
What do xylem cells transport?
Water
Xylem cells are hollow, allowing water to flow through them efficiently.
How are phloem and xylem cells structured?
Long and joined end to end
This structure forms tubes for transporting substances.
True or False: Most differentiation occurs in adult animals.
False
Most differentiation occurs during the early life stages of animals.
Fill in the blank: Cells that are specialised to carry out a specific function are called _______.
Specialised Cells
Specialised cells have unique structures that enable them to perform specific roles.
What is the primary function of chromosomes?
Chromosomes contain genetic information
What is the structure of chromosomes?
Coiled up lengths of DNA molecules
How many copies of each chromosome do body cells normally have?
Two copies
How many pairs of chromosomes are found in a human cell?
23 pairs
What is the cell cycle?
A series of stages that body cells undergo to divide and make new cells
What is the stage of the cell cycle when the cell divides?
Mitosis
What is the purpose of mitosis in multicellular organisms?
To grow and develop
What happens during the growth stage of the cell cycle?
The cell increases the amount of subcellular structures and DNA is replicated
Fill in the blank: Before it divides, the DNA forms _______ chromosomes.
X-shaped
What happens to the chromosomes during mitosis?
They line up at the center of the cell and are pulled apart to opposite ends
What occurs after the chromosomes are divided during mitosis?
The cytoplasm and cell membrane divide
What is the result of mitosis?
Two new cells that contain identical DNA to the original cell
True or False: Cells undergoing mitosis can be identified by their characteristic appearance under a microscope.
True
How can a student determine the percentage of cells undergoing mitosis?
By comparing the number of cells undergoing mitosis to the total number of cells counted
What subcellular structures increase in number during the growth phase of the cell cycle?
Ribosomes and mitochondria
What does the term ‘differentiated cell’ refer to?
A cell that has developed specific functions
What is an ‘indifferentiated cell’?
A cell that has not yet developed specific functions
What type of cells are produced at the end of mitosis?
Identical daughter cells
What are stem cells?
Undifferentiated cells that can differentiate into specialized cells and produce more undifferentiated cells.
What are embryonic stem cells?
Stem cells found in early human embryos that can turn into any kind of cell.
Where are adult stem cells found?
In certain places in the body, like bone marrow.
What types of specialized cells can adult stem cells produce?
Certain types, such as blood cells.
Can stem cells from embryos and bone marrow be cloned?
Yes, they can be cloned in a lab.
How can embryonic stem cells help in medicine?
They could replace faulty cells in sick people, e.g., making nerve cells for paralysis.
What is therapeutic cloning?
Making an embryo with the same genes as a patient to prevent rejection of stem cells.
What is a risk associated with using stem cells in medicine?
Stem cells could be infected with a virus, which could make a patient sicker.
What is a common argument against stem cell research?
Some believe embryos shouldn’t be used for research because they could be considered human life.
What is an argument in favor of stem cell research?
Curing patients who are suffering is more important than the rights of embryos.
What are meristems in plants?
Tissues where growth occurs, containing stem cells that can differentiate into any type of plant cell.
How can stem cells be used to clone plants?
They can make identical copies of plants quickly and cheaply.
What are some uses of plant cloning?
- Preserving rare species
- Creating crop plants with useful features
True or False: Stem cells can only be obtained from embryos.
False.
Fill in the blank: Adult stem cells can only produce _______ types of specialized cells.
certain
What are stem cells?
Undifferentiated cells that can produce more undifferentiated cells and differentiate into different types of cells.
What are embryonic stem cells?
Stem cells found in early human embryos that can turn into any kind of cell.
Where are adult stem cells primarily found?
In certain places in the body, like bone marrow.
What types of cells can adult stem cells produce?
Certain types of specialised cells, e.g. blood cells.
Can stem cells from embryos and bone marrow be cloned?
Yes, they can be cloned in a lab.
What is therapeutic cloning?
Creating an embryo with the same genes as a patient to avoid rejection of stem cells.
What is a potential risk of using stem cells in medicine?
Stem cells could be infected with a virus, which could make the patient sicker.
Why do some people oppose stem cell research?
They believe embryos shouldn’t be used for research because each could be a human life.
What argument do some people make in favor of stem cell research?
Curing suffering patients is more important than the rights of embryos.
What are meristems in plants?
Tissues where growth occurs, located in the tips of roots and shoots.
How can stem cells be used to preserve rare plant species?
By making clones (identical copies) of plants quickly and cheaply.
Fill in the blank: Stem cells can produce _______ plants.
identical
True or False: Adult stem cells can differentiate into any type of cell.
False
What type of stem cells can make nerve cells for people with paralysis?
Embryonic stem cells.
What is one use of stem cells in agriculture?
To create crop plants that have features useful for farmers.
What is diffusion?
Diffusion is the movement of particles from where there are lots of them to where there are fewer of them
It is also defined as the spreading out of particles from an area of higher concentration to an area of lower concentration.
In what states of matter does diffusion occur?
Diffusion occurs in solutions and gases
An example is the smell of perfume diffusing through the air.
What is the concentration gradient?
The difference in concentration
A larger concentration gradient results in a faster diffusion rate.
How does temperature affect the rate of diffusion?
A higher temperature increases the diffusion rate
This occurs because particles have more energy and move around faster.
What role do cell membranes play in diffusion?
Cell membranes allow substances to diffuse in and out of the cell
Only small molecules like oxygen, glucose, amino acids, and water can fit through.
Which types of molecules cannot pass through cell membranes?
Big molecules like starch and proteins cannot fit through cell membranes
Only very small molecules can diffuse through.
What determines the net movement of particles across a membrane?
The net movement is from where there’s a higher concentration to where there’s a lower concentration
Molecules can move both ways, but net movement is dependent on concentration differences.
How does the surface area of a membrane affect diffusion?
A larger surface area increases the rate of diffusion
More particles can pass through at the same time.
Fill in the blank: The movement of particles from an area of higher concentration to an area of lower concentration is known as _______.
[Diffusion]
True or False: Diffusion can only occur in solids.
False
Diffusion occurs in both solutions and gases.
What happens to a drop of ink added to cold water?
The drop of ink will gradually spread throughout the water
This is an example of diffusion in action.
How might the diffusion of ink differ in warm water compared to cold water?
In warm water, the ink will diffuse faster
This is due to increased particle energy and movement in warm conditions.
What is diffusion?
Diffusion is the movement of particles from where there are lots of them to where there are fewer of them
It is also defined as the spreading out of particles from an area of higher concentration to an area of lower concentration.
In what states of matter does diffusion occur?
Diffusion occurs in solutions and gases
An example is the smell of perfume diffusing through the air.
What is the concentration gradient?
The difference in concentration
A larger concentration gradient results in a faster diffusion rate.
How does temperature affect the rate of diffusion?
A higher temperature increases the diffusion rate
This occurs because particles have more energy and move around faster.
What role do cell membranes play in diffusion?
Cell membranes allow substances to diffuse in and out of the cell
Only small molecules like oxygen, glucose, amino acids, and water can fit through.
Which types of molecules cannot pass through cell membranes?
Big molecules like starch and proteins cannot fit through cell membranes
Only very small molecules can diffuse through.
What determines the net movement of particles across a membrane?
The net movement is from where there’s a higher concentration to where there’s a lower concentration
Molecules can move both ways, but net movement is dependent on concentration differences.
How does the surface area of a membrane affect diffusion?
A larger surface area increases the rate of diffusion
More particles can pass through at the same time.
Fill in the blank: The movement of particles from an area of higher concentration to an area of lower concentration is known as _______.
[Diffusion]
True or False: Diffusion can only occur in solids.
False
Diffusion occurs in both solutions and gases.
What happens to a drop of ink added to cold water?
The drop of ink will gradually spread throughout the water
This is an example of diffusion in action.
How might the diffusion of ink differ in warm water compared to cold water?
In warm water, the ink will diffuse faster
This is due to increased particle energy and movement in warm conditions.
What is osmosis?
The movement of water molecules across a partially permeable membrane from a less concentrated solution to a more concentrated solution.
What characterizes a partially permeable membrane?
A membrane with very small holes that allows tiny molecules like water to pass through, but not larger molecules like sucrose.
In osmosis, which direction do water molecules predominantly move?
From the less concentrated solution to the more concentrated solution.
What happens to the concentration of the more concentrated solution during osmosis?
It becomes more dilute.
What is the effect of osmosis on the concentration on either side of the membrane?
Water acts like it’s trying to ‘even up’ the concentration either side of the membrane.
What is the first step in observing the effect of sugar solutions on plant tissue?
Cut up a potato into cylinders with the same length and width.
What solutions are used in the practical experiment with potato cylinders?
Pure water and concentrated sugar solutions (e.g., 1 mol/dm³) along with less concentrated sugar solutions.
What should you measure before placing potato cylinders in the solutions?
The mass of each potato cylinder.
What indicates that water has moved into the potato cells after the experiment?
If the mass of the potato cylinders has increased.
What indicates that water has moved out of the potato cells?
If the mass of the potato cylinders has decreased.
What is the only variable that should change in the potato osmosis experiment?
The concentration of the sugar solution.
Fill in the blank: Osmosis is really just a fancy word for the _______.
diffusion of water molecules.
What do root hairs do for plants?
They increase the surface area for absorption of water and nutrients.
What is active transport in the context of root hairs?
The process used by root hairs to absorb nutrients against the concentration gradient.
True or False: Osmosis occurs only in plant cells.
False.
What should remain constant in the potato osmosis experiment?
Volume of solution, temperature, time, type of sugar used.
What are root hairs?
Root hairs are cells that cover plant roots and stick out into the soil
They provide a large surface area for absorbing water and mineral ions.
Why do plants need mineral ions?
Plants need mineral ions for healthy growth.
How do root hair cells absorb minerals from the soil?
Root hair cells absorb minerals using active transport.
Why can’t root hair cells use diffusion to take up minerals?
The concentration of minerals is usually higher in the root hair cells than in the soil.
What does active transport allow root hair cells to do?
Active transport allows root hair cells to absorb minerals from a very dilute solution in the soil against the concentration gradient.
What is required for active transport to function?
Active transport requires energy from respiration.
How is water taken into root hair cells?
Water is taken into root hair cells by osmosis.
What is the role of active transport in human nutrition?
Active transport helps the body absorb nutrients from food to survive.
What happens when there is a higher concentration of nutrients in the gut?
Nutrients diffuse into the blood.
What does the body do when there is a lower concentration of nutrients in the gut than in the blood?
The body uses active transport to move nutrients from the gut to the blood.
How does active transport affect glucose absorption?
Active transport allows glucose to be taken into the blood against the concentration gradient.
What happens to glucose after it is transported to the blood?
Glucose is transported to cells, where it is used for respiration.
True or False: Active transport does not require energy.
False
Fill in the blank: Active transport moves substances _______ the concentration gradient.
against
What factors influence how easily substances move between an organism and its environment?
The organism’s surface area to volume ratio
A higher surface area to volume ratio facilitates easier exchange of substances.
What is diffusion in the context of cellular exchange?
The process by which cells take in substances like oxygen and eliminate waste products like carbon dioxide and urea.
What is the significance of the surface area to volume ratio?
It determines how easily an organism can exchange substances with its environment.
How do you calculate the surface area of a block?
Using the equation: LENGTH x WIDTH.
What is the formula to calculate the volume of a block?
LENGTH x WIDTH x HEIGHT.
Calculate the surface area to volume ratio (SA:V) for a block measuring 4 cm x 4 cm x 2 cm.
The SA:V ratio is 2:1.
What is the SA:V ratio of a mouse represented by a 1 cm x 1 cm x 1 cm block?
The SA:V ratio is 6:1.
Explain the relationship between organism size and surface area to volume ratio.
Larger organisms have a smaller surface area compared to their volume.
True or False: A smaller surface area to volume ratio makes it harder for an organism to exchange substances.
True.
What is one way to make exchange surfaces more effective for organisms?
Having a large surface area.
What role do the alveoli play in gas exchange?
They facilitate the exchange of oxygen and carbon dioxide in the lungs.
What are the characteristics of alveoli that make them effective for gas exchange?
- Large surface area
- Very thin walls
- Good blood supply.
What is the function of villi in the intestines?
To increase the surface area for absorption of nutrients.
Fill in the blank: The surface area to volume ratio shows how big a shape’s surface is compared to its _______.
volume.
Give one reason why the human body has specialized exchange surfaces.
To efficiently exchange gases, nutrients, and waste.
What is the area to volume ratio?
It is the ratio of surface area to volume, significant for diffusion processes.
Why do single-celled organisms efficiently exchange substances?
They have a large surface area compared to their volume.
What do multicellular organisms require for substance exchange?
They need specialized exchange surfaces and transport systems.
List three adaptations of exchange surfaces in multicellular organisms.
- Thin membrane
- Large surface area
- Good blood supply
True or False: Multicellular organisms can exchange enough substances across their outside surface alone.
False
Where does gas exchange occur in the lungs?
In the alveoli.
What gases are exchanged in the lungs?
Oxygen (O2) and carbon dioxide (CO2).
What are the characteristics of alveoli that facilitate gas exchange?
- Large surface area
- Very thin walls
- Good blood supply
What is the role of villi in the small intestine?
To increase the surface area for faster absorption of digested food.
How do digested food substances move into the blood?
By diffusion and active transport.
Fill in the blank: The alveoli are specialized for the diffusion of _______ and _______.
[oxygen] and [carbon dioxide]
What condition causes inflammation of the small intestine and can damage the villi?
Coeliac disease.
Why might a person with coeliac disease have low levels of iron in their blood?
Damage to the villi reduces nutrient absorption, leading to low iron levels.
What diffuses through the stomata into the leaf?
Carbon dioxide
This process is essential for photosynthesis.
What substances diffuse out of the leaf through the stomata?
Oxygen and water vapour
This is part of the gas exchange process.
What controls the size of the stomata?
Guard cells
Guard cells regulate the opening and closing of stomata to control gas exchange.
How does the flattened shape of the leaf contribute to gas exchange?
Increases the area of its exchange surface
A larger surface area allows for more efficient diffusion.
What is another exchange surface inside the leaf?
The walls of the cells
Gases diffuse through these walls into and out of the cells.
What feature inside the leaf increases the area for gas exchange?
Air spaces
Air spaces facilitate the movement of gases within the leaf.
What are the gills in fish responsible for?
Gas exchange
Gills extract oxygen from water and expel carbon dioxide.
What happens to oxygen in the gills?
Diffuses from the water into the blood
This is how fish obtain oxygen for respiration.
What happens to carbon dioxide in the gills?
Diffuses from the blood into the water
This process helps maintain the fish’s internal gas balance.
What structural feature of gills provides a large surface area for gas exchange?
Thin plates
The thin plates increase the surface area available for diffusion.
What enhances the efficiency of gas exchange in gills?
A good blood supply from lots of blood capillaries
A rich blood supply ensures rapid transport of gases.
What type of cells are found in the gills that aid in gas exchange?
Thin layer of surface cells
Thin cells reduce the diffusion distance for gases.
What is the primary function of stomata in leaves?
Facilitate gas exchange
Stomata allow for the exchange of oxygen, carbon dioxide, and water vapour.
Fill in the blank: The process by which gases move from an area of high concentration to an area of low concentration is called ______.
Diffusion
Diffusion is a key mechanism in gas exchange.
True or False: Gills have a small surface area to optimize gas exchange.
False
Gills have a large surface area to maximize gas exchange efficiency.
