Module 2: Inheritance and survival

Module 2: Inheritance and survival

Chromosomes and variation
Candidates will be assessed on their ability to:

recall that each human body cell contains 23 pairs of chromosomes giving a diploid number of 46 (2.01)

understand that mitosis is the division of a cell to produce two cells with identical sets of chromosomes, for growth or replacement (2.02)

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) (2.03)

recall that each human gamete contains 23 chromosomes, the haploid number (2.04)

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) (2.05)

describe how the fusion of haploid male and female gametes (fertilisation) produces a diploid zygote (fertilised ovum or egg cell) (2.06)

explain how sexual reproduction, involving fertilisation, leads to variation in the new generation (2.07)

recall that individuals inherit some characteristics from their father through the sperm and some from their mother through the egg (2.08)

explain how the sex of an individual depends upon X and Y chromosomes and is determined at fertilisation (2.09)

describe the functions of the sex hormone testosterone in promoting secondary sexual characteristics in men (2.10)

describe the functions of the sex hormone oestrogen in promoting secondary sexual characteristics in women (2.11)

recall that oestrogen causes the lining of the uterus to thicken during the early part of the menstrual cycle (2.12)

recall that progesterone maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy (2.13)

recall that manufactured sex hormones can be used to treat infertility in women (2.14)

Genes and variation
Candidates will be assessed on their ability to:

understand that genes are parts of chromosomes which are found within the nucleus (2.15)

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) (2.16)

describe some of the implications of the outcome of the Human Genome Project (2.17)

understand how some inherited characteristics can be modified by environmental conditions, e.g. the influence of the mother�s diet or smoking on a baby�s birth weight (2.18)

explain how alternative forms of a gene (alleles) cause variation in a characteristic, to include eye colour (2.19)

recall that some alleles cause diseases which can be inherited (2.20)

understand the terms dominant and recessive (2.21)

describe the mechanism of monohybrid inheritance using genetic diagrams (2.22)

understand the terms homozygous, heterozygous, genotype and phenotype (2.23)

predict ratios of genotypes and phenotypes in a given monohybrid cross (2.24)

recall that a mutation is a change in the chemical structure of a gene (2.25)

recall that mutations can be caused by ionising radiation, including ultraviolet light, X-rays and gamma rays, and by some substances in tobacco (2.26)

describe how asexual reproduction leads to genetically identical individuals (clones) (2.27)

Genetically modified organisms

� Candidates will be assessed on their ability 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)

understand that crop plants can be genetically modified, and the reasons for doing so (2.29)

describe the potential benefits and ethical dilemmas posed by advances in genetic modification (2.30)

Selection, survival and evolution
Candidates will be assessed on their ability to:

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 (2.31)

describe how competition between individuals of the same species controls population size (2.32)

describe how the populations of predator and prey are dependent on each other (2.33)

describe how new species may evolve from variants which are better adapted to their environment (2.34)

understand that fossils provide evidence for evolution (2.35)

explain how natural selection can lead to evolution or extinction of species (2.36)

explain the principles of natural selection (2.37)

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 (2.38)

Population and human survival
Candidates will be assessed on their ability to:

recall that increasing population size leads to increased pollution (2.39)

interpret data on environmental change (2.40)

describe how human activity can affect the environment, especially changes in population size, and in economic and industrial conditions, given suitable information (2.41)

recall that burning fossil fuels releases harmful wastes into the air, especially smoke and acidic gases (2.42)

recall that acidic gases combine with water vapour to form acid rain which damages plants and animals (2.43)

recall that some harmful substances occur in vehicle exhaust gases, including carbon dioxide, carbon monoxide, nitrogen oxides (2.44)

describe how air pollution by vehicles can be reduced (2.45)