Chromosones and variation
You should be able to:
(2.01) recall that each human body cell
contains 23 pairs of chromosomes giving a diploid number of
46
(2.02) understand that
mitosis is the division of a cell to produce two cells with identical sets of chromosomes, for growth or
replacement
(2.03) describe the outcome of mitosis – the replication of each chromosome
and the separation of the
replicas (recall or use of technical terms is not required)
(2.04) recall that each human
gamete contains 23 chromosomes, the haploid number
(2.05) understand
that meiosis is the division of a diploid cell to produce four haploid cells
with sets of chromosomes that are
not genetically identical to produce gametes (sperm and
ovum) (recall or use of technical terms is not required)
(2.06) describe how the fusion of
haploid male and female gametes (fertilisation) produces a diploid
zygote (fertilised ovum or egg cell)
(2.07) explain how sexual reproduction, involving fertilisation, leads to
variation in the new generation
(2.08) recall that individuals inherit some characteristics from their father
through the sperm and some from their
mother through the egg
(2.09) explain how the sex of an individual depends upon X and Y chromosomes and
is determined at fertilisation
(2.10) describe the functions of the sex hormone testosterone in promoting
secondary sexual characteristics in
men
(2.11) describe the functions of the sex hormone oestrogen in promoting
secondary sexual characteristics in
women
(2.12) recall that oestrogen causes the lining of the uterus to thicken during
the early part of the menstrual cycle
(2.13) recall that progesterone maintains the lining of the uterus during the
middle part of the menstrual cycle
and during pregnancy
(2.14) recall that manufactured sex hormones can be used to treat infertility in
women
You should be able to:
(2.15) understand that genes are parts of
chromosomes which are found within the nucleus
(2.16) understand that the unit of inheritance is the gene which is a section of
a long chain (DNA) molecule; describe
a DNA molecule as two strands coiled to form a double helix, the strands
linked by a series of paired bases (adenine with thymine and cytosine with
guanine)
(2.17) describe some of the implications of the outcome of the Human Genome
Project
(2.18) understand
how some inherited characteristics can be modified by environmental conditions,
eg the influence of the mother’s diet or smoking on a baby’s birth weight
(2.19) explain
how alternative forms of a gene (alleles) cause variation in a characteristic,
to include eye colour (2.20) recall
that some alleles cause diseases which can be inherited
(2.21) understand the terms dominant and recessive
(2.22) describe the mechanism of monohybrid inheritance using genetic diagrams
(2.23) understand the terms
homozygous, heterozygous, genotype and phenotype
(2.24) predict ratios of genotypes and phenotypes in a given monohybrid cross
(2.25) recall that a mutation is
a change in the chemical structure of a gene
(2.26) recall that mutations can be caused by ionising radiation, including
ultraviolet light, X-rays and gamma rays, and by some substances in tobacco
(2.27) describe how asexual reproduction leads to genetically identical
individuals (clones)
You should be able to:
describe how the transfer of a
required gene from a donor to a recipient, including the use
of enzymes, can produce genetically modified organisms (2.28)
(2.29) understand that crop
plants can be genetically modified, and the reasons for doing so
(2.30) describe
the potential benefits and ethical dilemmas posed by advances in genetic
modification
You should be able to:
(2.31) understand how adaptations such as
– hair colour, hair length, size of ears in mammals
– gills, streamlined shape, mucus-covered scales in fish
– extensive roots, reduced leaves with thick cuticles in cacti
allow survival in particular environmental conditions
(2.32) describe how competition between individuals of the same species controls
population size
(2.33) describe how the populations of predator and prey are dependent on each
other
(2.34) describe
how new species may evolve from variants which are better adapted to their environment
(2.35) understand that fossils provide evidence for evolution
(2.36) explain how natural selection can lead to evolution or extinction of
species
(2.37) explain the principles of natural selection
(2.38) explain
how selective breeding (artificial selection) can be used, for example,
– in cattle to improve the quality and quantity of milk
– to increase the number of offspring in sheep
– to increase yield from dwarf wheat
Pollution and human survival
You should be able to:
(2.39) recall that increasing population
size leads to increased pollution
(2.40) interpret data on environmental change
(2.41) describe how human activity can affect the environment, especially
changes in population size, and in
(2.42) economic and industrial conditions, given suitable information
recall that burning fossil fuels releases harmful wastes into the air,
especially smoke and acidic gases
(2.43) recall that acidic gases combine with water vapour to form acid rain
which damages plants and animals
(2.44) recall that some harmful substances occur in vehicle exhaust gases,
including carbon dioxide, carbon
monoxide, nitrogen oxides
(2.45) describe how air pollution by vehicles can be reduced