Biology P1

• What are eukaryotic cells and their examples?

  they are cells with a nucleus. Plant and animal cells are eukaryotic cells.
• what are prokaryotic cells and examples?

  prokaryotic cells dont have a nucleus so are much smaller in comparison . e.g bacteria cells
• What are the difference between plants and animal cells?

  Animal cells have a nucleus , cytoplasm , cell membrane , mitochondria , ribosomes. Plant cells contain that but also include chloroplast , cell wall and permanent vacuole filled with cell sap
• what does a bacteria cell contain?

  cytoplasm , DNA loop , plasmid , cell wall
• what is the role of the nucleus?

  Genetic information storage and controls cell activities.
• what is the role of the cytoplasm?

  Site for most chemical reactions
• what is the role of cell membrane?

  To regulate the movement of substances in and out of the cell.
• what is the role of the mitochondria?

  Site for most aerobic respiration.
• what is the role of ribosomes?

  site for protein-synthesis
• what is the role of chloroplast?

  site for photosynthesis. they contain a green substance called chlorophyll which absorbs the light needed for photosynthesis.
• what is the role of the rigid cell wall?

  made of cellulose. it supports the cell and strengthens it.
• what is the role of the permanent vacuole?

  storage for cell sap , a weak solution of salts and sugars
• what is the role of the plasmids?


  Plasmids are segments of DNA
• What are nerve cells function and how are they specialised?

  nerve cells function is to carry electric signals from one part of the body to another. They are specialised for rapid signalling. They are long ( to cover more distance ) and have branched connections at their ends to connect to other nerve cells to form a network throughout the body.
• what are muscle cells function and what are they specialised for?

  muscle cells function is to contract quickly. they are specialised for contraction. the cells are long ( so they have space to contract ) , and contains lots of mitochondria to generate energy needed for contractions
• what are sperm cells function and how are they specialised?

  sperm cells are functioned to get male DNA to female DNA. they are specialised for reproduction. they have a long tail and streamlined head to help swim to egg. they have lots of mitochondria in the cell to provide energy. they carry enzymes in the head to digest through the egg cell membrane
• what is the function for a root hair cell and how are they specialised?

  they are functioned to uptake water. they are specialised for absorbing water and minerals. they are on the surface of plant roots , which grow into long hairs that stick out into the soil. this gives the plant a big surface are for absorbing water and mineral ions from the soil
• what is the function for an xylem and phloem and how are they specialised?

  they form phloem and xylem tubes, which transport substances such as food and water around plants. they are specialised for transporting substances. to form tubes the cells are long and joined end to end. xylem cells are hollow in the centre and phloem cells have very few subcellular functions so stuff can flow through them
• What is cell differentiation?

  process by which a cell changes to become specialised for its job. As an organism develops, cells differentiate to form different types of cells. Most type of animal cells differentiate at an early stage. Many plants cells have the ability to retain the ability to differentiate throughout life
• what are the cells that differentiate in mature animals used for?

  they are used for repairing and replacing cells such as skin or blood cells.
• How have microscopy techniques developed over time?

  Before we use light microscopes which use light and lenses to form an image of a specimen and magnify it . They let us see individual cells and large subcellular structures. Now we use electron microscopes which use electrons to form an image. They have a much higher magnification and higher resolution ( sharper image ).
• how have electron microscopes increased understanding of sub-cellular structures?

  Higher resolution and magnification of electron microscopes have allowed scientists to visualize and study sub-cellular structures in greater detail. they let us see smaller things in detail like internal structure of ribosomes and chloroplast.
• Formula for magnification?

  Magnification = size of image / size of real object
• microscopy PRACTICAL part 1?

  add drop of water to middle of a clean slide. cut up onion and separate it into layers , use tweezers to peel off some epidermal tissue from the bottom of one layer. using tweezers place epidermal tissue into the water on the slide. add a drop of iodine solution ( its a stain ). stains are used to highlight objects by adding colour to them. place a cover slip on top. try not to get any air bubbles under there as they will obstruct view of specimen.
• Microscopy PRACTICAL part 2?

  use light microscope to look at slide. Clip the slides you’ve prepared onto the stage. Select the lowest powered objective lens ( lowest magnification ). Use the coarse adjustment knob to move the stage downward until the image is roughly in focus. Adjust the focus with the fine adjustment knob , until u get a clear image of whats on the slide. If u need to see the slide with greater magnification , swap to a higher powered objective lens and refocus.
• where are chromosomes found and what do they carry?

  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.
• what is the cell cycle?

  series of events from growth and DNA replication to mitosis
• what happens during the cell cycle?

  the genetic info is doubled and then divided into two identical cells
• what happens during growth and DNA replication?

  before the cell divides , the cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes. it then duplicates its DNA so there’s one copy for each new cell. the DNA is copied and forms x shaped chromosomes.
• what happens during mitosis?

  the chromosomes line up at the centre of the cell and cell fibres pull them apart. the two arms of each chromosome go to opposite ends to the cell. membranes form around each set of chromosomes. these become the nuclei of the two new cells. the nucleus has divided. lastly, the cytoplasm and cell membrane divide. the cells have now produced two new daughter cells. they contain exactly the same DNA, they’re identical. the DNA is also identical to the parent cell
• what is a stem cell?

  an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same types.
• what is the function of stem cells in embryos ( embryonic stem cells ) ?

  they have the ability to differentiate into any type of cell in the body.
• what is the function of stem cells in embryos in adult animals?

  stem cells from adult bone marrow can form many type of cells including blood cells
• what can stem cells in embryos and bone marrow produce?

  they can be grown in a lab to produce clones and made to differentiate into specialised cells to use in medicine or research.
• how can stem cells be used to cure diseases?

  medicine already uses adult stem cells to cure diseases. e.g stem cells transferred from bone marrow of healthy person can be used to replace faulty blood cells.
• how can embryonic stem cells be used to cure diabetes?

  they can differentiate into insulin-producing cells
• how can embryonic stem cells be used to help people paralysed by spinal injuries?

  embryonic stem cells can differentiate into nerve cells.
• what can meristem tissues in plants differentiate to?

  meristem tissues in plants can differentiate into any type of plant cells , throughout the life of the plant. They can produce clones quickly and cheaply , used to grow more plants of rare species , grow crops with desired characteristic . ( e.g disease resistance )
• What happens in therapeutic cloning?

  an embryo is produced with the same genes as the patient. Stem cells from the embryo aren’t rejected by the patients body so they may be used for medical research
• what are some risks involved with using stem cells in medicine?

  viral infection can be transferred as its produced in a lab.