biology

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T-Level Biology

For the NCFE specification.

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Index for B1

Cells

Genetics

Particles and radiation

Cell cycle

Immunology

Units

Large molecules

Epidemiology and health promotion

Enzymes

Homeostasis and physiological measurements

Exchange and transport mechanisms

Classification of diseases and disorders

Index for B2

Musculoskeletal system

Nervous system

Cardiovascular system

Renal system

Respiratory system

Integumentary system

Digestive system

Reproductive system

Endocrine system

Cancer

This is a labelled diagram of an eukaryotic cell, namely animal cell.

CELLS

All life on Earth exists as cells, and these cells have basic features in common. Differences between cells are due to the addition of extra features. This provides indirect evidence for evolution. All cells arise from other cells, by binary fission in prokaryotic cells and by mitosis and meiosis in eukaryotic cells.All cells have a cell-surface membrane and, in addition, eukaryotic cells have internal membranes. The basic structure of these membranes is the same and enables control of the passage of substances across exchange surfaces by passive or active transport.

+cells info

THE CELL CYCLE

Mitosis is a part of cell division during which the nucleus of a cell is divided into two daughter nuclei having an identical number of chromosomes.The process of mitosis consists of the following phases; Prophase; during which the nuclear envelope degenerates, chromosomes become prominent, and the mitotic apparatus starts forming. Metaphase; In this phase, mitotic spindles are formed, attaching to the chromatids, pulling them and aligning along the mitotic plate. Anaphase; During this phase, chromosomes are segregated, and sister chromatids are pulled towards the opposite poles. Cell also begins to elongate. Telophase; it results in the formation of the nuclear envelope around the sister chromatids and two nuclei are formed

QUIZ

MITOSIS QUESTION

LARGE MOLCULES

YOU NEED TO KNOW ABOUT:

Proteins

Carbohydrates

Lipids

ENZYMES

The properties and functions of enzymes are determined by their structure:Properties:

• The shape of the active site
• The role of bonding
• The effect of temperature on enzyme function

Role of enzymes:

• Proteases including trypsin
• carbohydrases including amylase
• lipase

How the surface area to volume ratio and additional factors affect the rate of exchange and give rise to specialised systems:

EXCHANGE AND TRANSPORT MECHANISMS

• the surface area must be large in comparison to the volume for efficient exchange
• where the surface area is small compared to the volume, specialised exchange and transport mechanisms are required to maximise the rate of exchange

how additional factors affect the rate of exchange: - diffusion distance - temperature - metabolic rate

Extra from the spec:

Included in this part of the specification is also the role of the light microscope and how to calculate magnification It is important also to note the structure of different eukaryotic organelles, such as the golgi apparatus and vesticles, centrioles and lysosomes.

• It is important to note the different types of cells (prokaryotic and eukaryotic)

B1.11 The structure of the cell surface membrane and mechanisms of cellular exchange and transport:

• the fluid mosaic model of the cell surface membrane and how it facilitates cellular exchange and transport • passive transport through the cell surface membrane: diffusion, facilitated diffusion and osmosis • active transport through the cell surface membrane • co-transport mechanisms