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MDCAT Online Test Biology Unit 1
Before you attempt the online quiz take a review of key points Biology chapter 1 cell structure and its functions.
- The oldest accurately dated life form is a microorganism, Eu-bacterium
Isolated which dated back 3500 million years.
- The resolving power of a light microscope is 250nm, which is about 500X
that of the naked eye.
- The human naked eye can differentiate between two points at least
- The magnification power of a light microscope is as much as 10,000 times.
- Transmission electron microscope Item) can magnify an object up to
1,000,000 (I million) times.
- For 3D images of whole objects, a scanning electron microscope is used.
- The process in which different types of stain (dyes or color) are applied to
cell or part of the cell to %differentiate” or examine easily is called staining.
- The first stain applied to a component is called a principle stain.
- Counter Stain, the stain that makes cell structure more visible, when
not completely visible with the principle stain.
- Example: crystal violet stains only Gram-positive bacteria in Gram
staining. Safranin a counter stain is applied that stains all cells, allowing identification of Gram -ve bacteria.
- Vital Stain: non-toxic stain applied to cell or tissue which do not harm
- Types; Supra vital and intravital stain.
- Vital stain applied to a cell or tissue removed from a body is called
- Vital stain applied to a cell or tissue which is still the part of a body is
called intravital stain. ‘
- The culture of cell or tissue, organ (in vitro) outside the living bodies in a
nutrient artificial medium in antiseptic conditions is called tissue culture.
- Tissue culture is done on liquid nutrient medium i.e BROTH and AGAR or
semi-liquid nutrient medium.
- IN VIVO: The process inside the living e.g in-vitro fertilization.
- IN VITRO: The process occurs outside the living.
- The meristematic tissues are used in tissue culture because they are
rapidly dividing tissue, so most commonly the ex-plant of meristematic
- Sterilization: The process treatment of ex-plant with the antiseptic
the chemical is called sterilization.
The following chemical is most commonly use;
- Root formation is done with high auxin, low cytokinin ratio.
- Shoot-formation is done with low auxin, high cytokinin ratio.
- Callus formation occurs with the same auxin to cytokinin ratio.
- Cell wall is ABSENT in animal cells.
- Present in plant cell composed of cellulose.
- Present in fungi cell composed of chitin.
‘ 27. Present in a bacterial cell composed of murine or peptidoglycan.
- Cell wall is the secretion of Golgi bodies
- It is freely permeable.
- Cell wall is composed of the following three layers:
a. Outer – Middle lamella (1µm)
b. Middle – Primary wall (I to 3 µm)
c. Inner – Secondary wall (5 to 10 µm)
- Plant cell without a cell-wall is called protoplast.
- Nucleus + cytoplasm is called protoplasm.
- Cell membrane also called cell surface membrane or plasma membrane
and is found in all prokaryotic and eukaryotic cells.
- it lies below the cell wall.
- Cell membrane is composed of 60-80% protein and 20-40% lipids.
- Proteins of the cell membrane are extrinsic protein, intrinsic protein and
transport protein or permease.
- Extrinsic protein: These proteins are found on the surface of the membrane.
- Intrinsic proteins: These protein extend completely through the double
membrane from one side to another.
- Transport protein or perm-ease: Many small molecules and non-polar
molecule pass through lipid while large and polar molecule cannot pass
through lipids, they must pass with the help of a protein called permease.
- Transport of substances across the cell membrane through protein is
called facilitated transport:
- Facilitated transport may be;
- The movement of substances from a region of low concentration to high
concentration with the help of energy is called active transport.
- The movement of substances from a region of high concentration to low
concentration without the help of energy is called passive transport. It
occurs through gates.
- Active transport must occur with the help of special proteins called
- Proteins make the membrane selectively permeable because it selects the
transport of substance according to the need of cell.
- Cytoplasm consists of; Soluble part (cytosol)
- Insoluble part (cell organelle e.g. mitochondria, E.R, plastid)
- the cytosol contains 90% H2o and small ions which together form true
- Glycolysis occurs in the cytosol.
SO. The membrane of the endoplasmic reticulum is called cristae.
There are two types of endoplasmic reticulum i.e SER & RER.
- Rough E.R has ribosomes attached to its surface.
- Smooth E.R has no ribosomes.
- Smooth E.R helps in;lipid synthesis (especially steroid hormone synthesis)
Detoxification of harmful drugs. Muscle contraction Transmission of in; pulse
Mechanical support. In muscle cell E.R is called the sarcoplasmic reticulum
- Ribosomes synthesized in the nucleolus in a eukaryote,
- In eukaryotes the ribosome is of larger size (the 80S) with a smaller sub unit of
The 40s and a larger sub unit of 60s
Online Test Cell Structure & Functions