Bio Paper 1

• Eukaryotic cells contain DNA in the nucleus and forms chromosomes
• Cell membrane controls what substances enter and leave the cell
• The nucleus contains DNA
• Mitochondria is where respiration occurs and energy is released
• Ribosomes are where protein synthesis occurs
• The cytoplasm is a jelly like substance where chemical reactions happen
• A vacuole contains cell sap and is only in plant cells
• Chloroplasts contain chlorophyll to absorb light for photosynthesis and are only in plant cells
• The cell wall is made out of cellulose which strengthens the cell and is only found in plant cells
• Prokaryotic cells (bacteria) are single celled
• Prokaryotic cells have no nucleus and only a single loop of DNA
• Prokaryotic cells have small rings of DNA called plasmids
• Prokaryotic cells are smaller than eukaryotic cells
• Magnification is enlargening the specimen
• Resolution is the closest distance in which two points are distinguishable from each other
• A light microscope uses light to form an image whereas an electron microscope uses a beam of electrons
• With a light microscope living samples can be viewed whereas with an electron microscope samples cannot be living
• Light microscopes are relatively cheap and show colour whereas electron microscopes are expensive and do not show colour
• A light microscope has low magnification and low resolution
• An electron microscope has high magnification and high resolution
• Magnification= Image/actual
• A specialised cell is a cell that performs a specific function
• Most animals differentiate at any early stage of development whereas plant cells differentiate throughout their lifetime
• The function of a sperm cell is to fertilise an ovum
• The adaptations of a sperm cell include: a tail to swim to the egg and lots of mitochondria to release energy from respiration
• The function of a red blood cell is to transport oxygen around the body
• Adaptations of a red blood cell include: No nucleus so there is more room to carry oxygen, contains haemoglobin that binds to oxygen molecules and a flat bi-concave disc shape to increase the surface area to volume ratio
• The function of a muscle cell is to contract and relax to allow movement
• Adaptations of a muscle cell include: contains protein fibres which contract to make cells shorter, lots of mitochondria for energy release during respiration
• The function of a nerve cell is to carry electrical impulses around the body
• The adaptations of a nerve cell include: branched endings to connect with other neurones or effectors, axon is insulated by myelin sheath to increase transmission speed of electrical impulses, long to cover long distances
• The function of the root hair cell is to absorb mineral ions and water from the soil
• Adaptations of the root hair cell include: long projection increases surface area for absorption, lots of mitochondria for active transport of mineral ions from the soil
• The function of the palisade cell is to enable photosynthesis in leaves
• Adaptations of the palisade cell include: lots of chloroplasts containing chlorophyll to absorb light energy, located at the top surface of the leaf where it can absorb the most light energy
• The function of the phloem cell is to transport sugar in plants
• Adaptations of the phloem cell include: a long tube joined end to end to transport sugars
• The function of a xylem cell is to transport water in plants
• The adaptations of the xylem cell include: long tube joined end to end and hollow so water can pass
• Diffusion is the movement of particles from an area of high concentration to an area of low concentration