Variables -
Factors which may or may not influence the outcome of an experiment |
Control-
A parallel experiment where one variable is changed so that it
may be determined whether that variable affects the outcome |
Epidermis-
A tissue in plants which is normally the outermost layer of cells
used for protection. This layer normally does not perform photosynthesis |
Vascular
tissues- A tissue which functions to transport water
and sugars throughout the plant. Made up of : |
|
Xylem -
A tissue which functions to transport water, normally from the
roots upward
Phloem- A tissue which transports sugars from
areas of the plant where they are made to areas which need sugar |
Trichome -A
leaf hair. An extension of epidermal cells to provide protection
from drying or insects |
Stoma
(plural stomata) - An opening formed in the epidermal
layer of the leaf by specialized cells to allow air to enter
the leaf. These cells can open and close the hole to regulate
the uptake of air and the loss of water through evaporation (transpiration) |
Root
hair - An extension of epidermal cells on the root which
increases the contact between the root and soil to pick-up water
and minerals from the soil |
Ground
tissue - A tissue which is usually internal to the plant
and provides specialized functions- seed cortex, pith, parenchyma |
|
Cortex -
A ground tissue which is beneath the epidermis in plant stems and
root. It functions to store water and starch for the plant. In
green stemmed plants, it also functions to provide photosynthesis
Pith - A ground tissue which is in the center
of stems . It functions to store water and starch for the plant.
Palisade parenchyma (or mesophyll) - ground
tissue in the leaf which functions as the main photosynthetic
cells. They are packed closely together beneath the top epidermal
cells for maximum absorption of the light.
Spongy parenchyma (or mesophyll) - ground tissue
in the leaf which function in photosynthesis. This layer occurs
in the bottom half of the leaf and so receives less light than
the palisade parenchyma cells. Large air spaces between the cells
provide a means for air and water transport between cells.
|
Polymer-
a chain of similar compounds (building blocks) linked together |
Lipids -
A group of polymers built from fatty acids fatty acids. The long
carbon chains in the fatty acids are hydrophobic (repel water)
and so lipids usually separate from water and form membranes or
droplets |
Carbohydrates-
A group of polymers whose building blocks are monosaccharides.
Monosaccharides are single sugars (e.g. glucose), disaccharides
are two linked sugars (e.g. sucrose), starch, glycogen and cellulose
are polysaccharides of many glucose units linked together. |
Proteins-
a group of polymers made from amino acids linked end to end. The
chemical properties of a protein are determined by the type and
order of the amino acids. Proteins function as catalysts of specific
chemical reactions |
Nucleic
Acids- a group of polymers made up from nucleotide bases
(A, G, C, T, U) linked end to end. DNA is used for storing information,
RNA is a gene-size copy of the information from DNA which is
exported from the nucleus to produce a protein. Information in
nucleic acids is transferred by the A-T and G-C pairing rule. |
Membranes-
lipid layer which prevent movement of compounds from one side to
another and so forms compartments. Outer membrane separates cell
from outside; inside, membranes form organelles |
Cell
wall- outer layer of plant cells made of cellulose,
pectin (both carbohydrates) and lignin. It provides structural
strength to the cell. |
Cytoplasm-
watery gel-like material inside cell between organelles |
Organelles-
compartments inside the cell which perform specialized functions: |
|
-nucleus: stores
DNA, genetic information for building cell
-chromosomes are packaged DNA
-mitochondria: used for converting sugar to energy
-chloroplast: performs photosynthesis, only found in plants
-vacuole: storage closet of cell: acids, pigments, chemicals
|
Respiration -
The entire process where sugar is “burned” to produce
carbon dioxide. The energy released is saved as chemical energy
in the form of ATP and NADH. The three parts are: |
|
Glycolysis-
the splitting of the six carbon sugar into two three carbon compounds.
Releases only part of the energy but can take place in the absence
of oxygen
Kreb cycle- part of respiration
where the three carbon compound (from glycolysis)
is split into three molecules of carbon dioxide
(CO2)- a one-carbon compound. Energy is obtained
in the form of NADH.
Electron transport- the
process where the electron transfer from
NADH to oxygen (O2) is used to convert energy
stored in NADH into energy stored as ATP.
Needed to complete the extraction of energy
in respiration. |
Photosynthesis-
The process where the energy in light is captured to convert carbon
dioxide into sugar. The parts are: |
|
Light
reaction- Chlorophyll ( a pigment) absorbs light and
starts a process of electron transfers between proteins in the
chloroplast. These result in the production of ATP and NADPH
to store the energy. Chlorophyll takes an electron from water
to replace its lost electron, producing oxygen (O2).
Dark reaction -
the process which uses the energy
stored as ATP and NADPH to combine
CO2 (one carbon) into sugars (six-carbon
compounds). |
C4
plants- Plants which “pump” fixed carbon
dioxide into cells in the leaves so as to increase effective
CO2 levels in photosynthesis. Makes plants more efficient under
hot dry, bright conditions since CO2 levels are limiting for
photosynthesis. |
Energy
cycle- the movement of energy from sunlight into plants
and transfer in the food chain. Results in the cycling of carbon
from carbon dioxide into organic molecules like carbohydrates. |
Gene -
a segment of DNA which encodes a single protein (start, chain of
amino acids, stop) |
Codon-
a set of three nucleotides which encodes a specific amino amino
acid to be placed in a protein. Also punctuation (start, stop) codes. Together,
the 81 possible codons form the genetic code. |
Transcription-
the copying of information from a gene-length piece of DNA into
RNA. Uses the A-T G-C pairing to copy information. |
Translation-
the expression of the code of a gene encoded as nucleotide sequence
in RNA into the corresponding amino acid sequence in a protein.
Uses ribosomes (proteins) and tRNA (an adapter has nucleotide triplet
and attached to specific amino acid) to perform the copying through
A-T and G-C pairing |
Genome-
the entire set of genes in an organism which are encoded in the
DNA in each cell |
Chromosome-
a physical segment of the genome, similar in principle to volumes
of an encyclopedia |
Meristerm-
a point in the plant where cells divide, produces growth of the
plant |
Mitosis-
the division of the DNA of the cell such that a dividing cell can
produce two cells with exactly the same information in each cell. |
Meiosis-
a process used in sexual reproduction to produce 4 cells which
contain only one homologous chromosome of each type. Forms gametes
(pollen, ovules) used for fertilization. |
Sister
chromatids- Exact copies of a specific chromosome. Often
are joined together until mitosis or meiosis separates them. |
Homologous
chromosomes- set of two similar chromosomes. Encode
the same types of genes, but the exact information may be different.
Individuals usually inherit one from the male parent and the
other from the female parent |
Diploid -a
state of a cell having complete sets of two homologous chromosomes
(2n) |
Haploid -
a state of a cell having a single set of chromosomes (n) |
Gametes -
a haploid reproductive cells - sperm and eggs, pollen and ovules |
Zygote -
a fertilized egg or ovule- usually diploid |
Phenotype -
appearance of an individual - how the information is expressed |
Genotype -
genetic makeup- the information at each allele |
Alleles -
DNA sequence information that encodes a different phenotype for
a particular
gene (e.g. blue and brown eyes encoded by one gene that determines eye color) |
Homozygous
individuals - having identical alleles (one from each
parent) for a particular characteristic |
Heterozygous
individuals- having two different alleles for a particular
characteristic |
Dominant
allele- an allele of a certain gene which is able to
hide another allele in a heterozygous individual
(e.g. purple allele in the pea) |