bio - end of years

• Mitochondria are responsible for producing energy through respiration.
• The nucleus is the control center of the cell, containing DNA that controls all cellular activities.
• The nucleus is the control center of the cell, containing genetic material (DNA) that determines an organism's characteristics.
• Chloroplasts contain chlorophyll, which absorbs light energy to produce glucose during photosynthesis.
• Ribosomes synthesize proteins using information from DNA.
• Plant and animal cells (eukaryotic cells) have a cell membrane, cytoplasm and genetic material enclosed in a nucleus.
• Bacterial cells (prokaryotic cells) have cytoplasm and a cell membrane surrounded by a cell wall.
• Most animal cells have the following parts: • a nucleus • cytoplasm • a cell membrane • mitochondria • ribosomes.
• In addition to the parts found in animal cells, plant cells often have: chloroplasts and a permanent vacuole filled with cell sap.
• in plant cells cellulose strengthens the cell wall
• The sperm cell's function is to fertilise the female egg and so are classified as specialised cells. Sperm cells have a nucleus that contains genetic information.
• Nerve cells are required for the transmission of electrical impulses. Nerve cells send impulses around the body of animals in order to aid sensation and movement. Nerve cells are adapted to carrying impulses.
• Muscle cells contain filaments of protein that slide over each other to cause muscle contraction. The arrangement of these filaments causes the banded appearance of heart muscle and skeletal muscle. They contain many well-developed mitochondria to provide the energy for muscle contraction.
• Root hair cells absorb mineral ions by active transport, against the concentration gradient. They are adapted for taking up water and mineral ions by having a large surface area to increase the rate of absorption.
• The xylem is specialised to transport water up the stem of a plant and into the leaves.
• Phloem transports sugars from the leaves down through the stems to all parts of the plant where they can be used for respiration or stored as starch.
• magnification = size of image / size of real object
• The nucleus of a cell contains chromosomes made of DNA molecules. Each chromosome carries a large number of genes.
• In body cells the chromosomes are normally found in pairs.
• Cells divide in a series of stages called the cell cycle
• a chemical excreted by animals is urea
• a chemical stored in animal cells is glycogen
• a chemical stored in plant cells is starch
• multiply the length value by 1000 to convert millimetres into micrometres
• root hair cells don't contain chloroplasts because they are underground and therefore can't photosynthesise
• advantages of using stem cells would be: they can grow into any type of tissue and can be used in medical research
• in a plant stem cells are found in the meristems (the tips of roots and shoots)
• picogram to grams formula is 1 picogram is equal to 1 x 10^-12 grams
• nanograms to grams is 1 nanogram is equal to 10^-9 grams
• picograms to nanograms is 1 picogram is equal to 0.001 nanogram
• stage one of mitosis is interphase - cell growth and DNA respiration
• stage two - mitosis - the chromosomes line up in the middle before separation and through nuclear division 2 identical daughter cells are formed and moves to each side
• stage 3 - cell division - cytoplasm divides in order to form 2 new cells (cytokinesis)
• prokaryotic cells contain no organised nuclei unlike eukaryotic cells
• protein synthesis occurs in the ribosomes
• the larger the volume : surface area ratio the less amount of heat they will lose
• oxygen enters a single celled organism through diffusion
• cell membrane controls the movement of substances into and out of the cell
• Diffusion is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.
• Some of the substances transported in and out of cells by diffusion are oxygen and carbon dioxide in gas exchange, and of the waste product urea from cells into the blood plasma for excretion in the kidney.