Paper 1 Flashcards
(29 cards)
name 5 structures in an animal cell and their function
Ribosomes-where proteins are made
Cell membrane-holds together cells, controls what goes in and out
cytoplasm-gel like substance, where most chemical reactions take place
mitochondria-most aerobic reactions take place, site for photosynthesis
nucleus-contains genetic information
What structures do plant cells have that animal cells don’t have? Name their functions
Cell wall-supports cell, gives it structure, made of cellulose
permanent vacuole- contains cell sap, weak solution of sugars and salts
chloroplasts- where photosynthesis occurs, contains green pigment (chloroplasts) which absorbs sunlight for photosynthesis
name the structures in a bacteria cell
cell membrane, cell wall, cytoplasm and plasmids
plasmids-small ring of DNA
microscopy equation
magnification=imagine size/real size
how to prepare your slide for a microscope
1) add a drop of water in the middle of a clean slide
2)separate a cut onion into layers, use tweezers to pull of some epidermal tissue from the layers
3)place epidermal tissue into the water on the slide
4)add a drop of iodine solution to stain the objects in the cell
5)place a cover slip over the specimen preventing any air bubbles
how to use a microscope to look at your slide
1)clip slide you’ve prepared onto stage
2)select lowest powered magnification lens
3)use the coarse adjustment knob to move the stage up just below objective lens
4)look done eye piece. Use coarse adjustment knob to move stage downwards until imagine is roughly in focus
5)adjust focus with the fine adjustment knob until you get a clear image
how to draw your observations
1)draw what you see with sharp pencil
2)ensure drawing takes up half space provided and has unbroken clear lines
3)no colouring or shading
4)sub cellular structures should be in proportion
5)include title of what you’re drawing and write down magnification
6)label important features using straight lines
differentiation meaning?
a cell adapts to become specialised for its job
how are sperm cell specialised for reproduction?
Function is to get male DNA to female DNA
-long tail and stream lined head to swim to egg
-has lots of mitochondria in the cell to provide energy needed
-carries enzymes in head to help digest through egg cell membrane
how are nerve cells specialised for rapid signalling?
Function is to carry electrical signals from one part of the body to another
-long and have branched connections at their ends to connect to other nerves to form a network through the body
how are muscle cells specialised for contraction?
function is to contract quickly
-long and contains lots of mitochondria to generate energy needed for contraction
how are root hair cells specialised for absorbing water and minerals?
cells on the surface of plant root, which grow into long hair that stick out of the soil gives plant big surface area for absorbing water and minerals from soil
how are phloem and xylem cells specials for transporting substances?
They form phloem and xylem tubes which transport substances such as food and water around plants.
-long and joined end to end
-xylem cells are hollow in the centre and phloem cells have very few sub cellular structures, so stuff flows through them easier
-phloem cells have sieve plates, allows sugars to flow easily between cells
what is a chromosome?
A sub cellular structure in which contains genetic information within the nucleus
each chromosome carries a large number of gene
body cells usually have 2 copies of chromosomes, one from father and one from mother
what is the cell cycle and what is it used for?
cell cycle makes new cells for growth, repair and development
1)the cell divides, this is called mitosis
2)multicellular organisms use mitosis to grow or replace damaged cells
-cycle ends with 2 cells identical to the original with the same number of chromosomes
Explain growth and DNA replication before division
1) DNA is all spread out in long strings
2)before division, cell has to grow and increase amount of sub cellular structures e.g. mitochondria and ribosomes
3)it then duplicates its DNA so there is one copy for each new cell. The DNA is copied and forms X-shaped chromosomes. Each arms of chromosome is an exact copy of the other
explain the division in mitosis
1)chromosomes line up at the centre of the cell and cell fibres but then apart. 2 arms of each chromosome go to opposite ends of the cell
2)membranes form around each set of chromosomes (nuclei of the two cells). The nucleus has divided
3)cytoplasm and cell membrane divide
produces 2new daughter cells with identical DNA to each other and the parent cell
Explain what binary fission is and how it takes place
prokaryotic cells replicate through this process, the cell is split in 2
1)the circular DNA and plasmids replicate
2)the cells get bigger and the circular DNA strands move to opposite poles of the cell
3)cytoplasm begins to divide and new cell walls begin to form
4) 2 daughter cells are produced. Each daughter call has one copy of the circular DNA but variable numbers of copies of plasmids
warm temp and lots of nutrients maximises binary fission
what is a stem cell?
Undifferentiated cell which can divide to create more stem cells or develop into specialised cells
name the types of stem cells
1) Embryonic stem cells; found in early embryos, used for research and can specialise to be any cell
2)adult stem cells;only found in bone marrow, can only turn into limited range of cells e,g, red blood cells, used in bone marrow transplants
3)plant stem cells; found in growing areas e.g. shoots and roots (meristem), can make any type of plant cell, used to produce clones of plants quickly and cheaply
uses of stem cells?
used to treat diseases like diabetes and leukaemia, growing organs or tissue for transplants, cloning rare plant species
Advantage and disadvantage of using stem cells
A) embryonic stem cells can specialise to be any cell so can cure many diseases
B) it can be seen as unethical as it’s taking away potential life
where are stem cells found in plants?
meristem
what is diffusion?
the movement of particles from an area of high concentration to lower concentration
