Biology - B1 🫧

• A cell is the basic unit of all living things
• Prokaryotes are generally smaller in size than eukaryotes
• Prokaryotic cells divide by binary fission
• Eukaryotic cells divide by mitosis
• Animal and plant cells are examples of eukaryotic cells
• Bacterial cells are examples of prokaryotic cells
• The cell wall is made from cellulose and toughened with lignin
• Mitochondria releases energy by aerobic respiration
• Cytoplasm is the site of chemical reactions controlled by enzymes
• The nucleus contains genetic material (e.g DNA) and controls activities in the cell
• Chloroplasts absorb light energy for photosynthesis
• The vacuole is filled with cell sap to keep the cell turgid
• Bacteria cells have a loop of DNA instead of a nucleus
• The function of a sperm cell is to fertilise an egg
• The sperm cell has a flagella to swim to the egg cell and fertilisation occurs
• The function of a nerve cell is to carry electrical signals and impulses
• Muscle cells contain mitochondria to release energy to move
• Specialised cells are structured to carry out a specific function
• The function of a root hair cell is to absorb water and minerals from the soil
• Root hair cells have a large surface area to increase the rate of water and mineral absorption
• Root hair cells do not contain chloroplasts because they are found underground
• The function of the xylem is to transport water and mineral ions from the roots to the leaves in one direction
• Transpiration is the loss of water vapour from the stomata of a plant
• The xylem is made from dead tissue and it’s cell wall is strengthened with lignin
• The function is the phloem is to transport sugars from the leaves to the rest of the plant in both directions
• Phloem consists of sieve tube elements joined end-to-end by perforated membranes called sieve plates
• Phloem is made of living tissue
• Translocation is the movement of sugars and amino acids from the leaves to the rest of the plant
• When a cell differentiates, it forms sub-cellular structures
• An advantage of a light microscope is that it is cheaper and smaller to use, however it has a lower magnification and resolution
• An advantage of an electron microscope is that it has a higher magnification and resolution however it is expensive and harder to use
• Magnification is how many times larger an image is through a microscope compared to the real object
• Resolution is the ability to distinguish between two objects that are close together
• To calculate magnification you do the image size / actual size
• Bacteria multiply by binary fission
• Sterilising your equipment is important because it kills harmful microorganisms
• In the culturing practical, the petri dish should be incubated at 25C because this avoids any harmful bacteria growing
• The most effective antiseptic is determined by the paper disc with the largest zone of inhibition
• Stem cell are undifferentiated cells that can divide to produce more undifferentiated cells
• Stem cells can be used to clone plants