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Higher Biology
Revision Exercise
Unit 1
Cell Biology
Cell Variety / Absorption and Secretion
1) The ____
cell is the basic unit of life.
2) A ___________
unicellular organism consists of one cell which possesses a
variety of structures enabling it to perform all the functions necessary for
the maintenance of life.
3) A ____________
multicellular organism consists of more than one cell. In
advanced animals and plants these are arranged into tissues giving a
division of labour.
4) _________
Variation in cell structure exists between cells of one type of tissue
and cells of different tissues since cells are __________
specialised to perform
particular functions.
5) Cells absorb molecules in solution by ________,
diffusion osmosis and active
_________.
transport
6) The cell wall surrounding plant cells is made of ________
cellulose and is
______
freely permeable to solutions. It prevents the cell from ________
bursting when
water is absorbed.
7) The plasma __________
membrane surrounding the living contents of all cells is
selectively __________.
permeable It consists of protein and ____________
phospholipid
molecules thought to be arranged as in the fluid _______
mosaic model.
8) Tiny channels in the plasma membrane make it _______
porous and allow the
_______
passive transport of small molecules by diffusion and osmosis along a
concentration gradient.
9) Other chemical substances such as ions are ________
actively transported
across the plasma membrane _______
against a concentration gradient by
_______ carriers. This process requires _______.
protein
energy
Respiration
1) _____
ATP is a high energy compound able to release and _________
transfer
energy when it is required for cellular processes.
2) ATP is regenerated from _____
ADP and inorganic phosphate by the
process of _______________
phosphorylation using energy released during respiration.
3) Oxidation
_________ involves the removal of hydrogen from a substrate and the
release of energy; _________
reduction involves the addition of hydrogen to a
substrate and the consumption of energy.
4) Glycolysis
_________ is a biochemical pathway common to aerobic and
_________ respiration. It involves the breakdown of glucose to _______
anaerobic
pyruvic
acid in the cytoplasm of a cell with the net gain of two ATP.
5) In the presence of ______,
oxygen aerobic respiration occurs in the central
______ of mitochondria where the respiratory substrate is oxidised
matrix
during ______
Krebs’ Cycle and _________
hydrogen is released.
6) This hydrogen becomes temporarily bound to NAD
____, a coenzyme
which transfers it to the ___________
cytochrome system on the cristae of
____________ where energy is released and used to form ATP.
mitochondria
7) As a result of ________
aerobic respiration, one molecule of glucose yields 38
ATP. ______
Water and CO2 are the final metabolic products.
8) In the absence of oxygen, anaerobic respiration occurs and one
molecule of glucose yields 2 ATP. The final metabolic products are
________ and ______________
ethanol
carbon dioxide in plant cells and _____
lactic acid in animal
cells (and some bacteria).
Photosynthesis
1) Light is absorbed, reflected and ___________
transmitted by a leaf.
2) The photosynthetic pigments from a leaf can be separated by
_______________.
chromatography
3) Chlorophyll absorbs light primarily in the ____
red and _____
blue regions of
the spectrum of white light. _______
yellow pigments absorb blue-green light.
4) The quantity of light absorbed by a pigment at different wavelengths
of light can be presented as a graph called an __________
absorption spectrum; the
rate of photosynthesis that occurs in a plant at different wavelengths of
action spectrum.
light can be presented as a graph called an ______
5) Chloroplasts possess internal structures called _______
grana which contain
photosynthetic pigments and are the site of the ______________
light-dependent stage of
photosynthesis. The region between grana is called the _______.
stroma It is the
carbon fixation stage of photosynthesis.
site of the ______________
6) The light-dependent stage of photosynthesis is called __________.
photolysis It
produces the energy (held in _____)
ATP and hydrogen needed for the second
stage (carbon fixation).
7) The second stage consists of a ______
cycle of reactions which brings about
the _________
reduction of carbon dioxide using the ATP and _________
hydrogen from
photolysis to form carbohydrate.
8) Photosynthesis is affected by temperature, light intensity and
_____________
carbon dioxide concentration. Its rate is therefore _______
limited by
whichever one of these factors is in short supply.
DNA and its Replication / Protein Synthesis
1) DNA consists of two strands twisted into a double ________.
helix
Each
strand is composed of ____________.
nucleotides Each nucleotide consists of
______________
deoxyribose sugar, phosphate and one of four types of base
( _________,
adenine thymine, _________
guanine or cytosine).
2) Adenine always pairs with _________;
thymine guanine always pairs with
_________.
cytosine
3) DNA is unique because it is able to reproduce itself by ___________.
replication
This allows the genetic message to be passed on from cell to _____
cell and
generation to generation.
4) RNA consists of a single strand of nucleotides. ________
Uracil is found in
place of thymine; ________
ribose replaces deoxyribose.
5) The bases along a DNA strand take the form of a molecular language
called the genetic _____.
code Each _______
triplet of bases codes for a particular
amino acid.
6) Messenger RNA (mRNA) is ___________
transcribed from a strand of DNA and
carries this genetic message from the nucleus out into the cytoplasm. At a
_________,
ribosome mRNA meets molecules of ________
transferRNA (tRNA) each
carrying a specific amino acid.
7) Protein synthesis occurs in ribosomes; mRNA’s triplet of bases, called
_______,
codons are read and matched by tRNA’s ___________.
anticodons This enables
peptide ______
bonds to form between adjacent amino acids.
8) Rough ____________
endoplasmic reticulum bears ribosomes on its outer
surface.
9) Freshly synthesised protein is transported via the endoplasmic
reticulum to the ______
Golgi apparatus where it is processed and packaged in
________.
vesicles
10) Some protein is _________
secreted out of the cell by vesicles moving
towards, and fusing with, the plasma membrane.
11) In addition to carbon, hydrogen and oxygen, proteins always contain
________.
nitrogen
12) A protein consists of sub-units called ____________
amino acids (of which there
are about 20 types) joined together by peptide bonds to form
polypeptides.
13) A molecule of _______
fibrous protein consists of parallel ____________
polypeptide
chains and has a structural function.
14) A molecule of _________
globular protein consists of polypeptide chains
folded into a spherical shape. Some are structural (eg. Those in the
plasma membrane); others act as _________,
enzymes hormones or __________.
antibodies
Cellular Defence
1) ________
Viruses exhibit living and non-living characteristics and can only
reproduce within the living cells of another organism.
2) A virus consists of one type of _______
nucleic acid surrounded by a coat of
_______.
protein
3) Once inside a host cell, the virus alters the _____
host cell’s metabolism to
produce many identical copies of itself.
4) The two main ________
defence mechanisms employed by the human body
depend on the activities of ______
white blood cells.
5) Phagocytes engulf and destroy microbes by ____________
phagocytosis using
lysosomes. This is a ____________
non-specific response.
6) _____________
Lymphocytes recognise antigens on the surface of a microbe and
produce ___________.
antibodies These possess receptor sites which bind to one
particular type of ________
antigen rendering it harmless. This is a ________
specific
immune response.
7) Plants do not make antibodies. They defend themselves against
invasion by producing toxic compounds such as ________,
nicotine cyanide and
________.
tannins
8) Some plants can isolate an area of injury by secreting sticky ______.
resin
End