IGCSE Biology Specification

Edexcel 4BI1

Section 3: (b) Inheritance

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#3.14

understand that the genome is the entire DNA of an organism and that a gene is a section of a molecule of DNA that codes for a specific protein

#3.15

understand that the nucleus of a cell contains chromosomes on which genes arelocated

#3.16B

describe a DNA molecule as two strands coiled to form a double helix, the strands being linked by a series of paired bases: adenine (A) with thymine (T), and cytosine (C) with guanine (G)

#3.17B

understand that an RNA molecule is single stranded and contains uracil (U) instead of thymine (T)

#3.18B

describe the stages of protein synthesis including transcription and translation, including the role of mRNA, ribosomes, tRNA, codons andanticodons

#3.19

understand how genes exist in alternative forms called alleles which give rise to differences in inherited characteristics

#3.20

understand the meaning of the terms: dominant, recessive, homozygous, heterozygous, phenotype, and genotype

#3.21B

understand the meaning of the term codominance

#3.22

understand that most phenotypic features are the result of polygenic inheritance rather than single genes

#3.23

describe patterns of monohybrid inheritance using a genetic diagram

#3.24

understand how to interpret family pedigrees

#3.25

predict probabilities of outcomes from monohybrid crosses

#3.26

understand how the sex of a person is controlled by one pair of chromosomes, XX in a female and XY in a male

#3.27

describe the determination of the sex of offspring at fertilisation, using a genetic diagram

#3.28

understand how division of a diploid cell by mitosis produces two cells that contain identical sets of chromosomes

#3.29

understand that mitosis occurs during growth, repair, cloning and asexual reproduction

#3.30

understand how division of a cell by meiosis produces four cells, each with half the number of chromosomes, and that this results in the formation of genetically different haploid gametes

#3.31

understand how random fertilisation produces genetic variation of offspring

#3.32

know that in human cells the diploid number of chromosomes is 46 and the haploid number is 23

#3.33

understand that variation within a species can be genetic, environmental, or a combination of both

#3.34

understand that mutation is a rare, random change in genetic material that can be inherited

#3.35B

understand how a change in DNA can affect the phenotype by altering the sequence of amino acids in a protein

#3.36B

understand how most genetic mutations have no effect on the phenotype, some have a small effect and rarely do they have a significant effect

#3.37B

understand that the incidence of mutations can be increased by exposure to ionising radiation (for example, gamma rays, x-rays and ultraviolet rays) and some chemical mutagens (for example, chemicals in tobacco)

#3.38

explain Darwin’s theory of evolution by natural selection

#3.39

understand how resistance to antibiotics can increase in bacterial populations, and appreciate how such an increase can lead to infections being difficult to control