B2+B3 Flashcards
What happens in each stage of the cell cycle?
Interphase- cells grow, replicate DNA to make 2 copies of each chromosome and make more organelles
Mitosis- One set of chromosomes pulled to each side and cell divides
Cytokinesis- Cytoplasm and cell membrane divide forming 2 identical cells
Why is it easier to clone plants than animals?
Plant cells retain the ability to differentiate into all different types of cell
Name two potential uses for stem cells:
Treating:
-Vision loss
-Diabetes, by producing insulin-secreting cells
-Paralysis
Name four benefits of cloning plants:
-Saving rare plants from extinction
-Producing large populations of genetically identical plants for research
-Large numbers of exotic plants can be produced for sale
-Plants with resistant genes can be cloned, which could be helpful in agriculture
Name some problems with stem cell research:
-Ethical objection- the embryo can’t consent
-Religious objection- interfering w/ natural processes of reproduction
-Process is slow and expensive
-Cells divide so rapidly that there is a concern for cancer
-Viral infections
How are the villi adapted for nutrient absorption?
-Project from the SI increasing surface area
-Epithelial lining covered in microvilli further increases surface area
-Good blood supply for uptake of nutrients
-Thin wall provides short diffusion path
Describe each of the tests for each food group:
Carbohydrates:
-Iodine test- yellow-red turns blue-black if starch present
-Benedict’s test- blue solution turns red/orange/green upon heating if reducing sugars are present (colour varies depending on concentration)
Proteins:
-Biuret test- blue reagent turns purple if protein present
Lipids:
-Ethanol test- ethanol gives a cloudy white layer if lipids present
What processes can enzymes carry out?
They can break down and synthesise molecules
What is one function of bile?
(That doesn’t involve pH levels)
Emulsifies fats- breaks them into small droplets so there is a greater area for lipase enzymes to work on
How can someone with a mild Salmonella infection prevent the spread of bacteria to others?
Meant to be in B5, can’t be bothered to move it
-Wash hands after using the toilet/ being sick
-Wash hands before
preparing / handling food
-Do not prepare food
-Isolate yourself
-Disinfect clothes / surfaces
-Do not share utensils / cutlery / towels
Explain how amylase breaks down starch using lock and key theory:
-Substrate binds to active site
-Shape of active site and substrate are
complementary
-Bonds between the molecules are broken to
produce smaller molecules
Why do plants transpire less at night?
The stomata are closed because it is cooler
What is the role of lipids in the body?
They store energy, can be used for cell membranes and provide insulation
Why is having fewer stomata on the surface of a leaf an advantage?
Less water is lost, so the plant does not wilt
