B1 Cell Level System Flashcards
What are the drawbacks of electron microscopy?
Limited sample preparation, high cost, and cannot view live cells
Electron microscopy requires extensive sample preparation, which may alter the specimen. It is also expensive and cannot be used for live cell imaging.
What are the benefits of light microscopy?
Relatively low cost, ability to view live cells, and simple sample preparation
Light microscopy allows for the observation of living samples, is more affordable compared to electron microscopy, and requires less complex preparation methods.
What is a polymer?
A large molecule made up of repeating subunits called monomers
Polymers are formed through polymerization, where monomers chemically bond to form long chains.
What is a monomer?
A small, single unit that can join together to form a polymer
Monomers are the building blocks of polymers, such as glucose for starch.
What chemical reaction happens in mitochondria?
Aerobic respiration
Mitochondria are the sites of aerobic respiration where glucose and oxygen are converted into energy.
Where does CO2 enter the leaf and water and O2 leave it?
Through the stomata
Stomata are small openings on the leaf surface that regulate gas exchange.
What are the food stores found in animal and plant cells?
Animal cells: glycogen; Plant cells: starch
Glycogen serves as the energy reserve in animal cells, while starch is the storage form of energy in plants.
Where does photosynthesis take place?
In the chloroplasts of plant cells
Chloroplasts contain chlorophyll, which captures light energy for photosynthesis.
Why aren’t ribosomes visible under a light microscope?
They are too small, typically around 20 nm
Ribosomes are smaller than the resolution limit of light microscopes, making them invisible under this type of microscopy.
How to test a leaf for starch?
Boil the leaf, immerse in alcohol, and add iodine solution
The presence of starch is indicated by a blue-black color after iodine is added.
How many mm in 1 micrometer?
0.001 mm
1 micrometer (µm) is one-thousandth of a millimeter.
How many micrometers in 1 nanometer?
0.001 micrometers
1 nanometer (nm) is one-thousandth of a micrometer.
How many chromosomes in a human skin cell?
46 chromosomes
Human somatic cells, such as skin cells, contain 46 chromosomes arranged in 23 pairs.
What is an enzyme?
A biological catalyst that speeds up chemical reactions
Enzymes lower the activation energy required for reactions to occur.
Explain the term ‘exothermic reaction’
A reaction that releases energy, usually in the form of heat
Exothermic reactions result in products with lower energy than the reactants.
Write a balanced symbol equation of photosynthesis.
6CO2 + 6H2O -> C6H12O6 + 6O2
This equation represents the conversion of carbon dioxide and water into glucose and oxygen using light energy.
Describe the process of photosynthesis and give the word equation.
Photosynthesis converts light energy into chemical energy in glucose. Word equation: Carbon dioxide + Water -> Glucose + Oxygen
Photosynthesis primarily occurs in the chloroplasts of plant cells.
What are the four bases of DNA? How are they paired?
Adenine, Thymine, Cytosine, Guanine; A pairs with T, C pairs with G
The complementary base pairing is crucial for the structure of DNA.
Describe the practical method to ‘see’ stomata.
Use clear nail polish to make an impression of the leaf surface
After applying nail polish, the impression can be viewed under a microscope to observe stomata.
Describe the process of anaerobic respiration and give the equation.
Anaerobic respiration occurs without oxygen, producing lactic acid in animals or ethanol and CO2 in yeast. Equation: Glucose -> Lactic acid + Energy or Glucose -> Ethanol + CO2 + Energy
Anaerobic respiration is less efficient than aerobic respiration.
Explain the effect of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis.
Increased temperature and light intensity enhance the rate; carbon dioxide concentration also boosts photosynthesis until a saturation point
Each factor has an optimal range for maximizing photosynthesis.
Describe how enzymes work. Use diagrams.
Enzymes bind to substrates at the active site, forming an enzyme-substrate complex, which lowers activation energy for the reaction
Diagrams often illustrate the lock and key model or the induced fit model.
What is denaturing?
The process where an enzyme loses its shape and functionality due to extreme conditions
Factors such as high temperature or extreme pH can cause denaturation.
Describe how to test the effect of light intensity on the rate of photosynthesis.
Use a water plant like Elodea and measure the number of oxygen bubbles produced at different distances from a light source
This experiment demonstrates the relationship between light intensity and photosynthesis rate.
Describe the process of aerobic respiration and give the equation.
Aerobic respiration uses oxygen to convert glucose into carbon dioxide, water, and energy. Equation: Glucose + Oxygen -> Carbon dioxide + Water + Energy
This process occurs in the mitochondria of cells.
Explain the term ‘endothermic reaction’
A reaction that absorbs energy from its surroundings
Endothermic reactions result in products with higher energy than the reactants.
What does the term ‘producer’ mean?
An organism that produces its own food, typically through photosynthesis
Producers form the base of the food chain, providing energy for other organisms.
What is the role of a nucleus?
To store genetic material and control cell activities
The nucleus is often referred to as the control center of the cell.
What are carbohydrates made from?
Carbon, hydrogen, and oxygen
Carbohydrates are composed of simple sugars and can be classified as monosaccharides, disaccharides, or polysaccharides.
What are proteins made from?
Amino acids
Proteins are polymers formed from 20 different amino acids linked by peptide bonds.
What are fats made from?
Glycerol and fatty acids
Fats are a type of lipid that provide energy and insulation.
