Intermediate 2 Biology
Environmental Biology and Genetics
Unit 2
Chapters 8, 9 and 10 Summary
In mammals, sperm are produced in _______________ and _________ are produced in
ovaries; in flowering plants, the ____________ contain pollen and the __________
contain egg cells.
During fertilisation the nuclei of the two gametes fuse to form a _____________. This
process produces variety within the species since each zygote receives genetic information
from two ___________________ parents.
Chromosomes contain deoxyribonucleic acid (_________) which consists of two strands
each bearing a chain of _______________ molecules. The _______________ of bases
present in a region of DNA represents a series of codes words. These pass on a message
that determines the sequence of _________ acids in, and the structure of, a particular
_______________.
Each body cell of a multicellular organism has two matching sets of
___________________. During _______________ formation (meiosis), matching
chromosomes pair up and then __________________ again. Each gamete formed
receives one but not both members of a pair of chromosomes giving it a ____________
set of chromosomes.
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VM 2008
Biology Department
The separation of the members of a pair of chromosomes during meiosis occurs
___________ of the separation of all other pairs. This ‘shuffling’ of chromosomes leads to
_____________ in the gametes and in the offspring produced.
Each body cell of a human _______________ contains two X chromosomes; each body
cell of human male contains one X and one ___ chromosome.
All human eggs receive an X chromosome; half of the sperm receive an X and half a Y
chromosome. The sex of a human individual is ________________ by the type of ______
that fertilises the egg.
An organism’s physical characteristics are known collectively as its _________________;
an organisms characteristics are determined by _____________ information received from
both of its _________________.
Each inherited characteristic is controlled by one or more units of heredity called
__________; each gene is part of a chromosome.
Each gene normally has two or more different forms called _____________. An allele that
always shows its effect and masks the presence of the other form is said to be
_______________; an allele that is masked by the dominant form is said to be
_________________.
Each gamete carries only one allele of a gene; each zygote formed at
_________________ receives two alleles for each gene, one from each parent.
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Biology Department
The complete set of genes possessed by an organism is called its ___________________.
The genotype of an organism with identical alleles of a gene is described as
____________________; the genotype of an organism with two different alleles of a gene
is described as _________________________.
An experimental cross involving one difference between two true-breeding parents is
called a _______________________ cross. All members of the F1 generation resembles
the parent with the dominant allele. Selfing of the F1 produces an F2 generation with a
phenotypic _________ of 3:1.
An organisms phenotype is a result of the interaction between its genotype and the
__________________. Differences in phenotype caused by differences in genotype are
______________ and passed on from generation to generation. Differences in phenotype
caused by environmental factors are not passed on to the next ___________________.
Those members of species that are better ______________ to the environment survive to
_______________ age and pass on the ________________ characteristics to succeeding
generations; those members less well suited fail to do so. This survival of the ‘fittest’ in
each generation is called ______________ selection.
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Biology Department
Genetic ______________________ allows pieces of DNA to be cut out of one organism
and be __________________ into another organism which then forms a substance new to
that species.
__________________ bacteria can be used as chemical _______________ to produce
useful products such as human ______________.
Unlike selective __________________ genetic engineering allows scientists to alter an
organisms genotype ___________________ so that it will produce exactly what is
required immediately.
adapted
alleles
amino
anthers
base
breeding
chromosomes
determined
different
directly
DNA
dominant
eggs
engineering
environment
factories
female
fertilisation
gametes
generation
genes
genotype
heterozygous
homozygous
independently
inherited
inserted
insulin
monohybrid
natural
ovaries
parents
phenotype
protein
ratio
recessive
reproductive
reprogrammed
separate
sequence
single
sperm
testes
variety
Y
zygote
Charleston Academy
VM 2008
Biology Department
favourable