biology topic 2

The cell theory unifies all living things. The cell membrane separates the cell from its surroundings and controls the exchange of materials, nutrients, and wastes, between the cell and its environment. Describe and represent the fluid mosaic model of the cell membrane.

The major types of cell are prokaryotic and eukaryotic. Prokaryotic and eukaryotic cells have many features in common, which is a reflection of their common evolutionary past. Compare prokaryotic and eukaryotic cells with respect to their: size, internal organisation, shape and location of chromosomes. Prokaryotes only exist as single cells. Eukaryotic cells have specialised organelles which facilitate biochemical processes. Represent the structure and describe the function of: Nucleus, nuc

Cells require inputs of suitable forms of energy, including light energy or chemical energy in complex molecules - Distinguish between autotrophs and heterotrophs. Energy transformations occur within cells. The sun is the main source of energy for life. Recognise that photosynthesis is important in the conversion of light energy into chemical energy Recognise that energy is required to break chemical bonds and energy is released when new bonds are formed. Describe the formation of ATP from

Substances move in and out of cells by processes such as: diffusion, facilitated diffusion, osmosis, active transport, endocytosis, exocytosis. Explain how the structure of a membrane facilitates different processes of movement through it. Explain how factors affect the exchange of materials across membranes including: surface-area-to-volume ratio of the cell, concentration gradients, the physical and chemical nature of the materials being exchanged. Cells require an input of matter, includin

Cell metabolism is critical to the survival of cells. Biochemical processes in the cell are influenced by: the nature and arrangement of internal membranes Explain how the structure of internal membranes of mitochondria and chloroplasts facilitate some biochemical processes. the presence of specific enzymes Explain that in a metabolic pathway: there are many regulated steps, each step loses some energy as heat, some steps produce intermediate compounds, specific enzymes are required at each s

Cells arise from pre-existing cells, and cell division leads to an increase in cell number. Cell division in somatic cells is different from the cell division that produces gametes from germ-line cells. Continuity of life requires the replication of genetic material and its transfer to the next generation through processes including binary fission, mitosis, meiosis, and fertilisation. Explain why the amount of DNA in a cell doubles before division. The products of mitotic division or binary f

Diploid cells contain pairs of homologous chromosomes. Recognise, describe, and represent the process of meiosis in eukaryotic cells. Explain why the products of meiosis are haploid cells and contain a single set of chromosomes. Explain the importance of crossing over and independent assortment in meiosis. Explain that fertilization restores the diploid number. Compare the products of meiotic and mitotic cell division. Compare the sources and degree of genetic variation between the products

Cell division may be regulated by internal and external factors. The cell produces gene products that regulate the cell cycle. Describe the stages in the cell cycle (including checkpoints). Explain that hormones may regulate cell division. Carcinogens upset the normal controls of cell division by causing mutations. Human beings culture cells for a variety of purposes. Describe techniques of cell culture, and discuss the applications and limitations of contemporary examples of their use.