Organisation Flashcards
What are the stages of cell division by mitosis?
The cell grows and increases the number of organelles. The DNA replicates to form two copies of each chromosome
One set of the duplicated chromosomes is pulled to each end of the cell and the nucleus divides
Finally, the cytoplasm and cell membrane divide in a process called cytokinesis to form two identical daughter cells
What is the function of the digestive system?
Digestion and absorption by breaking down large insoluble food molecules into smaller soluble molecules
What are the roles of bile in digestion?
- Emulsifying lipids, breaking them up into tiny droplets which have a much larger surface area over which lipase can work
- Neutralises stomach acid and produces the optimum pH for enzymes
What is an enzyme?
A biological catalyst that speeds up chemical reactions
What is the ‘lock and key theory’?
The substrate of the reaction to be catalysed fits into the active site of an enzyme. Once in place, the enzyme and substrate bind together. The reaction takes place rapidly and the products are released from the surface of the enzyme
In what conditions would an enzyme denature?
In extreme pH or extreme temperature
Where is carbohydrase produced?
The pancreas, stomach and mouth (salivary glands)
Where is protease produced?
Small intestine, pancreas, stomach
Where is lipase produced?
Small intestine, pancreas, stomach
What is the route oxygenated blood takes from the lungs to the body?
Lungs → pulmonary vein → left atrium → left ventricle → aorta → body
What is the route deoxygenated blood takes from the body to the lungs?
Body → vena cava → right atrium → right ventricle → pulmonary artery → lungs
How is a red blood cell adapted for its function?
Flattened, biconcave disc shape to ensure a large surface area for efficient diffusion of oxygen. Has no nucleus or organelles to maximise space for haemoglobin so more oxygen can be transported
What are the functions of white blood cells?
They are part of the immune system and composed of lymphocytes which produce antibodies and antitoxins and phagocytes which engulf and digest invading microorganisms
What is the function of platelets?
To clot the blood and form scabs while new skin grows underneath
What is the structure of platelets?
Small fragments of cells without a nucleus
What are some of the substances carried in plasma?
Red blood cells, white blood cells, platelets, antibodies, nutrients, glucose, urea
How are arteries adapted to their function?
To carry blood away from the heart under high pressure, they have small lumen and thick walls