IAL Biology Specification Checklist for Unit 2 Topic 3

Know that all living organisms are made of cells , sharing some common features.

Understand how the cells of multicellular organisms are organised into tissues , tissues into organs , and organs into organ systems .

(i) Know the ultrastructure of eukaryotic cells , including nucleus , nucleolus , ribosomes , rough endoplasmic reticulum (rER) , smooth endoplasmic reticulum (sER) , mitochondria , centrioles , lysosomes and Golgi apparatus .

(ii) Understand the function of the organelles listed in (i).

Understand the role of the rough endoplasmic reticulum (rER) and the Golgi apparatus in protein transport within cells , including their role in the formation of extracellular enzymes .

(i) Know the ultrastructure of prokaryotic cells , including cell wall , capsule , plasmid , flagellum , pili , ribosomes and circular DNA .

(ii) Understand the function of the structures listed in (i).

Be able to recognise the organelles in 3.3 from electron microscope (EM) images.

(i) Know how magnification and resolution can be achieved using light and electron microscopy .

(ii) Understand the importance of staining specimens in microscopy.

(i) Use a light microscope to make observations and labelled drawings of suitable animal cells .

(ii) Use a graticule with a microscope to make measurements and understand the concept of scale.

(i) Know that a locus is the location of genes on a chromosome .

(ii) Understand the linkage of genes on a chromosome .

Understand the role of meiosis in ensuring genetic variation through production of non-identical gametes as a consequence of independent assortment in metaphase I and crossing over of alleles in prophase I . Names of the stages of prophase are not required.

Understand how mammalian gametes are specialised for their functions (including the acrosome in sperm and the zona pellucida in the egg cell ).

Know the process of fertilisation in mammals, including the acrosome reaction , cortical reaction and fusion of nuclei .

Know the process of fertilisation in flowering plants, starting with growth of a pollen tube and ending with fusion of nuclei .

Investigate factors affecting growth of pollen tubes .

Understand the role of mitosis and the cell cycle in producing genetically identical daughter cells for growth and asexual reproduction .

Prepare and stain a root tip squash to observe stages of mitosis .

Be able to calculate mitotic indices .

(i) Understand what is meant by the terms stem cell , pluripotent , totipotent , morula and blastocyst .

(ii) Discuss how society uses scientific knowledge to make decisions about use of stem cells in medical therapies.

Understand how cells become specialised through differential gene expression , producing active mRNA and proteins that control cell processes or determine cell structure in animals and plants.

Understand how one gene can give rise to more than one protein through post-transcriptional changes to messenger RNA (mRNA) .

(i) Understand how phenotype is the result of interaction between genotype and environment .

(ii) Know how epigenetic modification , including DNA methylation and histone modification , can alter activation of certain genes .

(iii) Understand how epigenetic modifications can be passed on following cell division .

Understand how some phenotypes are affected by multiple alleles for the same gene , or by polygenic inheritance , as well as the environment , and how polygenic inheritance

EDEXCEL IAL BIOLOGY

Specification 2025 - 2026

Unit 2

Topic 3 – Cell Structure, Reproduction and Development

3.1 Cell Basics

3.2 Organisation of Multicellular Organisms

3.3 Ultrastructure of Eukaryotic Cells

3.4 Protein Transport within Cells

3.5 Ultrastructure of Prokaryotic Cells

3.6 Recognising Organelles

3.7 Microscopy

3.8 CORE PRACTICAL 5

3.9 Gene Location and Linkage

3.10 Role of Meiosis

3.11 Specialisation of Mammalian Gametes

3.12 Fertilisation in Mammals

3.13 Fertilisation in Flowering Plants

Recommended Additional Practical

3.14 Role of Mitosis and the Cell Cycle

3.15 CORE PRACTICAL 6

3.16 Calculating Mitotic Indices

3.17 Stem Cells

3.18 Cell Specialisation

3.19 Post-Transcriptional Changes

3.20 Phenotype and Genotype

3.21 Polygenic Inheritance and Continuous Variation