biology 3 Flashcards
cells and cell proceeses
Define the Term Cell:
A cell is the basic structural and functional unit of all living organisms.
- Identify Eukaryotic and Prokaryotic Cells:
Eukaryotic cells have a nucleus and organelles (e.g., plant and animal cells).
Prokaryotic cells lack a nucleus and organelles (e.g., bacteria).
- Structures of Plant and Animal Cells:
Plant cells: Have a cell wall, chloroplasts, vacuole, nucleus, cytoplasm, ribosomes, Golgi complex, lysosomes, RER and SER.
Animal cells: Have a nucleus, cytoplasm, ribosomes, Golgi complex, lysosomes, RER and SER, but no cell wall or chloroplasts.
- Functions of Structures in Plant and Animal Cells:
Cell wall: Provides support and structure (only in plants).
Chloroplasts: Conducts photosynthesis (only in plants).
Vacuole: Stores water, nutrients, and waste.
Nucleus: Controls cell activities and contains DNA.
Cytoplasm: Site of chemical reactions.
Ribosomes: Protein synthesis.
Golgi complex: Modifies and packages proteins.
Lysosomes: Digest waste.
RER: Synthesizes proteins.
SER: Synthesizes lipid
- Relating Cell Structure to Function:
Ciliated cells: Have hair-like structures (cilia) to move substances.
Blood cells: Red blood cells are biconcave for oxygen transport.
Sperm and egg cells: Specialised for reproduction, sperm has a tail for movement, egg contains nutrients for development.
Root hair cells: Increase surface area for water and mineral absorption.
Xylem vessels: Hollow to transport water.
Palisade mesophyll cells: Contain chloroplasts for photosynthesis.
Nerve cells: Long axons for transmitting electrical signals.
- Levels of Organisation:
Tissue: A group of similar cells performing a specific function (e.g., muscle tissue).
Organ: A structure made of tissues performing a specific function (e.g., heart).
Organ system: A group of organs working together (e.g., digestive system).
- Calculate Magnification and Size of Biological Specimens:
Magnification = Image size / Actual size.
Actual size = Image size / Magnification.
- Define Diffusion:
Diffusion is the net movement of molecules from high to low concentration without energy input, down a concentration gradient.
- Factors Affecting Diffusion:
Surface area, temperature, and concentration gradient affect the rate of diffusion. Distance: The shorter the distance, the faster the diffusion.
- Diffusion as a Passive Process:
Diffusion does not require ATP (energy) as it relies on the kinetic energy of molecules.
- Investigating Factors Affecting Diffusion:
Experiment with temperature or concentration gradient to observe changes in diffusion rate.
- Define Osmosis:
Osmosis is the diffusion of water through a partially permeable membrane from a high water potential (dilute solution) to low water potential (concentrated solution).
- Define Terms:
Turgid: Plant cell swells with water.
Turgor pressure: The pressure within the plant cell due to water uptake.
Plasmolysis: The shrinking of the plant cell membrane away from the cell wall due to water loss.
Flaccid: A plant cell with reduced turgor pressure.
- Effects of Solutions of Different Concentrations on Plant Tissue:
Hypotonic solution: Water enters the cell, causing it to become turgid.
Hypertonic solution: Water leaves the cell, causing plasmolysis.
- Importance of Water Potential and Osmosis in Plants and Animals:
Water potential and osmosis are crucial for water uptake in plants and maintaining cell turgidity.
In animals, osmosis regulates fluid balance in cells.
- Plant Support by Turgor Pressure:
Plants are supported by the turgor pressure within cells, created by the inelastic cell wall that resists expansion.
- Define Active Transport:
Active transport is the movement of ions or molecules against a concentration gradient using energy (from respiration), e.g., root hair cells uptake of minerals, glucose absorption in the small intestine.
- Protein Molecules in Active Transport:
Proteins in the cell membrane help move large or charged particles during active transport.
