Biology unit 2 definitions

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  • Created by: Kamila
  • Created on: 27-05-13 15:44
Affinity
degree of attraction
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allele
an alternative form of a gene
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amylopectin
one of the 2 polysaccharides that make up starch. A branched polymer of starch
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amylose
one of the 2 polysaccharides that make up starch. An unbranched polymer of starch
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anaphase
phase of mitosis in which the chromatids split at the centromere and are pulled to opposite poles by the spindle fibres
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apoplast pathway
pathway taken by water travelling through the outer surface of the root to the xylem in the centre of the root. Water moves through the gaps between the cells
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antibiotic
an anti-bacterial drag
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artificial selection
selective breeding, where human activity directs natural selection
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bacteria
simple, single-celled prokaryotic organism
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base
in nucleic acids (DNA and RNA), one of 4 nitrogen-containing compounds. In DNA there are Adenine, Thymine, Cytosine and Guanine. RNA has Uracil instead of Thymine
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Binomial
having 2 names: the current classification system
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biodiversity
a measure of the no. of different species in a particular ecosystem
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Bohr effect
in presence of carbon dioxide, the affinity of haemoglobin for oxygen is lower
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carcinogen
cancer-causing agent
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casparian *****
layer of waterproof material around the endodermis in a plant root. It blocks the apoplast pathway
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cellulose
unbranched polymer of beta glucose. Forms long chains that bond to parallel chains via hydrogen bonds, forming fibres of great strength. Found in plant cell walls
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cell wall
outer protective coat secreted by cells of certain organisms
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centromere
the point of attachment of 2 chromatids on a double chromosome
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chemotherapy
using drugs to treat cancer
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chiasmata
in meiosis, the points of crossover; sites where chromosomes break and join to others
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chloroplast
plant organelle that is the site of the photosynthesis
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chromatid
one half of a double chromosome
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cohesion tension
mechanism by which water passes up the xylem of a plant, from roots to leaves. The cohesion of water allows a continuous columns under great tension
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conjugation
mechanism of gene transfer between bacteria in direct contact with each other. Involves copying and transfer of plasmids
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countercurrent system
when fluid flows in parallel tubes in opposite directions. Max. efficiency of material exchange by maintaining a diffusion gradient along the whole length of the system
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crossover
in meiosis, the procewss that swaps blocks of genes between homologous chromosomes. Creates new combinations of alleles, so increasing variation
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differentiation
when a stem cell becomes specialised
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diploid
a cell/organism that contains 2 sets of chromosomes
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diversity
a measure of the no. of different species in a community
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DNA
deoxyribonucleic acid
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DNA hybridisation
technique that estimates the evolutionary closeness of different species by comparing the similarity of their DNA sequences
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DNA polymerase
catalyses the addition of complementary nucleotides on the exposed strands
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DNA replication
the copying of DNA molecule. The 2 strands unwind and act as templates for the creation of 2 identical copies
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exons
in a gene, the base sequences that are expressed
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gamete
a sex cell
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gene
a section of DNA that contains a coded information for making polypeptides
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Vertical gene transmission
involves passing genes on from one generation to the next
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horizontal gene transmission
genes are passed from one species to another
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genetic code
the base sequence of the DNA molecule
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genotype
the alleles that an organism has
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glycogen
main storage material in animals
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Haemoglobin
a protein on red blood cells that transport oxygen
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haploid
a cell/organism that has a single set of chromosomes
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DNA helicase
unwinds and separates the 2 strands of DNA prior to replication or transcription
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hierarchy
in taxonomy, a layered system of groups, with no overlap
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hydrostatic pressure
the physical pressure of fluid
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independent assortment
separates the homologous chromosomes so that any one of a pair of alleles can pass into a gamete with one from any other pair
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prophase
1st stage of mitosis, in which chromosomes condense, the spindle develops and the nuclear membrane disappears
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random fertilisation
any egg can be fertilised by any sperm
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synthesis S phase
in interphase, time in which the DNA replicate
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standard deviation
a measure of spread of data about the mean
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starch
main storage carbohydrate in plants
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stomata
pores mainly on the underside of a leaf; allow gas exchange
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symplast pathway
pathway taken by water through a plant root from the outside to the xylem in the centre. Water moves through the living cytoplasm within cells
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taxonomy
science of classificiation
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telophase
in mitosis, the final stage of nuclear division, before cytokinesis. Cells in telophase have 2 separate nuclei, because the 2 sets of chromatids reached the poles
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triplet
in DNA, a group of 3 bases that codes for a particular amino acid aka codon
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zygote
a fertilised egg
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Other cards in this set

Card 2

Front

an alternative form of a gene

Back

allele

Card 3

Front

one of the 2 polysaccharides that make up starch. A branched polymer of starch

Back

Preview of the back of card 3

Card 4

Front

one of the 2 polysaccharides that make up starch. An unbranched polymer of starch

Back

Preview of the back of card 4

Card 5

Front

phase of mitosis in which the chromatids split at the centromere and are pulled to opposite poles by the spindle fibres

Back

Preview of the back of card 5
View more cards

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