Biology Paper 2 Consolidation Flashcards
Describe how an impulse passes from the relay neuron to the motor neuron.
- Synapse/ synaptic cleft is a gap between neurones
- Impulse in relay neuron triggers production of neurotransmitters
- Neurotransmitters diffuse across the synapse/ synaptic cleft
- New impulse triggered in motor neuron
Explain the function of a reflex arc.
- A process that occurs in response to danger
- Bypasses the brain/ involuntary process
- So there is faster transmission of electrical impulses allowing faster response
- To protect the body from harm
Explain why people with AIDS are more susceptible to TB.
- HIV destroys white blood cells/ weaken the immune system
- So the body is unable to destroy the TB pathogens/ prevent the pathogens from invading the body
A student placed a prepared slide on the stage of a light microscope.
Describe how to adjust the microscope to view the slide at a magnification of *400.
- Use the *40 objective lens
- Use the *10 eyepiece lens
Arthritis is a condition that occurs when cells in joints get damaged or destroyed. Stem cell therapy can be used to treat arthritis.
Discuss the benefits and risks of using stem cell therapy to treat arthritis.
- Stem cells can differentiate and become specialized
- Replace damaged cells
- Reduce symptoms of arthritis
- New cells do not function correctly
- Stem cells continue to divide
- Rejecting cells
A student wanted to extract the DNA from the fresh peas. The student crushed the peas and added washing up liquid and water. The enzyme protease was then added to this mixture.
Explain why the enzyme protease was added to the mixture.
- Protease breaks down proteins
- In the cell membrane
- Destroys enzymes that may break down the DNA
A student wanted to extract the DNA from the fresh peas. The student crushed the peas and added washing up liquid and water. The enzyme protease was then added to this mixture.
The mixture was then heated and filtered. Finally, the student poured the filtrate into a test tube and ice cold ethanol was poured down the side of the test tube into the filtrate.
State why ice cold ethanol was poured into the filtrate.
- To precipitate the DNA
- DNA is insoluble in ethanol
HIV is a sexually transmitted infection.
Explain how HIV can lead to the onset of AIDS.
- HIV destroys/ reduces the no. of white blood cells
- Which compromises the immune system
- AIDS makes the person more susceptible to other diseases
A student investigated the fat content of milk. Before starting the investigation, the student added a drop of oil from a pipette into a test tube of water. The drop of oil rose to the surface of the water.
5 cm ^3 of milk and 1 cm^3 were added to the test tube. The pH of this mixture was pH 7. This test tube was placed in a water bath for 10 minutes. There was no change in the pH of this mixture after 10 minutes.
Explain why there was no change in the pH of the mixture containing milk.
- Milk didn’t contain any/ much fat
- Fatty acids are not produced
- There was no substrate for lipase
A student was investigating mitosis in the roots of a garlic plant.
Describe how the student could prepare a microscope slide to show mitosis in the growing roots of a garlic plant.
- Use the root tip/ meristem
- Soften the root with alcohol/ heat/ acid
- Crush the root onto the slide/ Take a thin section
- Stain the root
- Add a drop of water to the slide
- Add a coverslip
Describe how the human’s limb provides scientists evidence for evolution from other vertebrates.
- Pentadactyl limb
- Common ancestor between humans and other vertebrates
- Structure has been adapted to different functions
State why scientists are genetically engineering animals for organ transplants.
Not enough human donors are available
Different enzymes catalyze specific reactions.
Explain why enzymes can only catalyze specific reactions.
- Active site of an enzyme has a specific shape because of the order of amino acids
- The substrate must have a complementary shape to the active site
Herbicide is sprayed onto the leaves of plants.
Suggest which vessel could transport the herbicide from the leaf to other parts of the plant.
Phloem
Suggest reasons for the increase in herbicide resistant weed species.
- Increased use of herbicide resistant crops
- Increase use of herbicide
- Cross pollination
- Mutation
