Cell Biology Flashcards
What are the two main types of cells?
Prokaryotic and eukaryotic cells.
Define a prokaryotic cell.
A prokaryotic cell is a simple, single-celled organism without a nucleus; its genetic material is free-floating within the cell.
Bacteria are examples of prokaryotes.
Define a eukaryotic cell.
A eukaryotic cell is a complex cell that contains a nucleus enclosed within membranes and other membrane-bound organelles.
Examples include plant and animal cells.
List three structures found in plant cells but not in animal cells.
Cell wall, chloroplasts, and a large permanent vacuole.
What is the function of the nucleus in a cell?
The nucleus controls the cell’s activities and contains the genetic material (DNA).
Where does aerobic respiration occur within the cell?
Aerobic respiration occurs in the mitochondria.
What is the role of ribosomes in a cell?
Ribosomes are the sites of protein synthesis, where amino acids are assembled into proteins.
Describe the function of the cell membrane.
The cell membrane controls the movement of substances into and out of the cell, providing a selective barrier.
What is the purpose of the cell wall in plant cells?
The cell wall provides structural support and protection; it is made of cellulose.
Explain the function of chloroplasts.
Chloroplasts contain chlorophyll and are the site of photosynthesis, where light energy is converted into chemical energy in plants.
What is the role of the permanent vacuole in plant cells?
The permanent vacuole maintains cell rigidity (turgor), stores nutrients and waste products, and helps in the growth of the plant cell.
Define cell differentiation.
Cell differentiation is the process by which a cell becomes specialized to perform a specific function.
What is a stem cell?
A stem cell is an undifferentiated cell that has the potential to develop into various specialized cell types.
Name the process by which cells divide to produce identical daughter cells.
Mitosis.
What is the significance of mitosis in multicellular organisms?
Mitosis is essential for growth, tissue repair, and asexual reproduction in multicellular organisms.
Define diffusion.
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration until equilibrium is reached.
What factors affect the rate of diffusion?
Factors include temperature, concentration gradient, surface area, and the distance over which diffusion occurs.
Explain osmosis.
Osmosis is the diffusion of water molecules across a selectively permeable membrane from a region of higher water concentration (or lower solute concentration) to a region of lower water concentration (or higher solute concentration).
What is active transport, and how does it differ from passive transport?
Active transport is the movement of substances against their concentration gradient, requiring energy (ATP). In contrast, passive transport (such as diffusion and osmosis) does not require energy and occurs along the concentration gradient.
Why are electron microscopes advantageous over light microscopes?
Electron microscopes have a higher resolution and magnification than light microscopes, allowing for more detailed visualization of cell structures.
What is cell differentiation?
Cell differentiation is the process by which a cell becomes specialized to perform a specific function.
What adaptations do root hair cells have to aid their function?
Root hair cells have long extensions that increase surface area for water and mineral absorption from the soil.
Define a stem cell.
A stem cell is an undifferentiated cell capable of dividing to produce either more stem cells or specialized cells.
Where are stem cells found in adult humans?
In adult humans, stem cells are primarily found in bone marrow.
What is the difference between embryonic stem cells and adult stem cells?
Embryonic stem cells can differentiate into any cell type in the body, while adult stem cells are typically limited to differentiating into cell types of their tissue of origin.
List two potential uses of stem cells in medicine.
- Treating diseases like Parkinson’s by replacing damaged cells.
- Repairing damaged tissues, such as heart tissue after a heart attack.
What are meristems in plants?
Meristems are regions in plants containing stem cells that can differentiate into various cell types, allowing for growth throughout the plant’s life.
Why is there ethical controversy surrounding the use of embryonic stem cells?
The use of embryonic stem cells is controversial because it involves the destruction of embryos, raising ethical concerns about the beginning of human life.
What is diffusion?
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration.
Give an example of a substance that moves into cells by diffusion.
Oxygen diffuses into cells for respiration.
What factors affect the rate of diffusion?
The rate of diffusion is affected by temperature, concentration gradient, and surface area of the membrane.
Define osmosis.
Osmosis is the diffusion of water molecules across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration.
What happens to a plant cell in a hypotonic solution?
In a hypotonic solution, water enters the plant cell by osmosis, causing it to become turgid (swollen).
What is active transport?
Active transport is the movement of substances against their concentration gradient, from a region of lower concentration to a region of higher concentration, using energy from respiration.
Give an example of active transport in the human body.
The absorption of glucose in the small intestine is an example of active transport.
How do root hair cells use active transport?
Root hair cells actively transport mineral ions from the soil into the plant against the concentration gradient.
What is the role of carrier proteins in active transport?
Carrier proteins in the cell membrane bind to specific molecules and use energy to change shape, transporting the molecules across the membrane.
How does surface area to volume ratio affect the rate of diffusion?
A larger surface area to volume ratio increases the rate of diffusion, as there is more surface area for substances to diffuse across relative to the cell’s volume.
Why is osmosis important for plant cells?
Osmosis helps maintain turgor pressure in plant cells, which keeps them rigid and supports the plant structure.
How do temperature changes affect the rate of diffusion?
Increasing temperature increases the kinetic energy of particles, leading to a faster rate of diffusion.
Why do multicellular organisms need specialised transport systems?
In multicellular organisms, cells are not in direct contact with the external environment, so specialized transport systems are needed to deliver nutrients and remove waste products efficiently.
