Structures and functions in living organisms Flashcards
(23 cards)
Jan 2020 1BR Q8 EYE
Name the structures labelled A,B,C and D
A=Iris
B=Cornea
C=Pupil
D=Lens
Jan 2020 1BR Q8
Ciliary muscles relaxes(1), which allows the suspensory ligament to pull tight(1). This makes the lens go thinner(1). So the light refracted by a smaller amount(1).
Describe the role of the stomach
Jan 2020 1BR Q1
The stomach produces hydrochloric acid(1) to kill bacteria and create the optimum pH for enzymes. It also secretes the enzyme pepsin(protease) to break down proteins into peptides(short chain of amino acid).
November 2023 1B
Explain the changes that will take place in solution X in test tube A and in test tube B(3)
Tube A stays clear. Tube B goes cloudy. More CO2 in exhaled air in tube B
What is excretion?
The removal of metabolic waste from the body.
Explain how iris controls the light entering the eye when someone walks into a dark room(2)
The brain tells the radial muscles to contract(1), which makes the pupil bigger(1).
Explain the change in breathing rate during the 12minutes of exercise(3)
Nov.2024 Q5
As the time spent exercising increases the breathing rate rises to take in more oxygen(1) for aerobic respiration(1). It also helps to remove(release) more carbon dioxide produced by the muscules(1). Eventually, the breathing rate stops increasing as it reaches a maximum level(1)
Nov2024 Q5
Explain why the breathing rate would remain high for a few minutes after the exercise has finished
Oxygen is required to remove lactic acid that builds up during anaerobic respiration. Repaying the oxygen debt
Nov 2024
Which structure contains villi
Small intestine
June 2022
Describe three other differences between the nervous system and the
hormonal system.(3)
- Nervous system uses neurones while hormonal system uses hormones carried in the blood.(1)
- Type of message-Nerve signals are electrical, whereas hormones are chemical
- Nerve responses act on specific target cell, but hormones can affect many parts of the body.(1)
Describe the pathway of a nerve impulse in the reflex arc involved in this response
- Receptor generates the impulse
- Impulse passes along the sensory neurone (to relay/motor neurone)
- The motor neurone then carries impulse to an effector.
- The impulse crosses synapses between neurones using neurotransmitters.
Explain two differences between the structure of the wall of an artery and the wall of a vein
- Artery has a thicker(more elastic) wall to carry blood under higher blood pressure
- Veins have valves to prevent blood backflow
Explain why, during exercise, the heart of a person with CHD would not respond as efficiently as the heart of a healthy person
During exercise, a person with CHD has narrowed or blocked arteries, so less blood can flow to the heart muscle. As a result, less oxygen reaches the heart muscle, leading to a reduction in aerobic respiration. This means less energy (ATP) is produced, so the heart cannot contract as strongly or beat faster to meet the body’s increased demands during exercise.
Suggest why the human gut only has a small caecum and appendix
Humans do not digest cellulose
2022 jan. Explain how these bacteria help the rabbits with their diet of plant material
Rabbits eat plants, which contain cellulose in their cell walls. Bacteria in the rabbit’s gut produce the enzyme cellulase, which digests the cellulose into glucose. The glucose is then used in respiration to release energy for the rabbit.
Explain how aphids feeding from the phloem of crop plants can lead to a reduction in yield
Aphids feed on the phloem and remove sugars like sucrose from the crop plants. This reduces the amount of carbohydrates available for respiration, so the plant produces less ATP (energy). As a result, there is less active transport of minerals, and the plant cannot grow as effectively, producing fewer leaves, fruits, or grains, which leads to a lower yield.
Name two substances the aphids obtain from the phloem
- Sucrose
- AMino acids
What two substances are found in xylem?
- Water
- Mineral ions
Explain why co2 needs to be absorbed by the soda lime when measuring the rate of aerobic respiration(2)
Soda lime absorbs co2, which only allows oxygen consumption measurement.
Explain the effect of increasing the temperature on the movement of the bubble
(respiration)
Increasing the temperature increases the kinetic energy of molecules, so they move faster. This causes them to collide more frequently, forming more enzyme-substrate complexes, which increases the rate of respiration. As a result, more oxygen is used, which causes the bubble to move faster in the apparatus.
what is meant by a reflex response
Unconscious message
Name three differences between bacteria and virus
Virus
1. smaller
2. protein coat
3. no cell wall
4. no cell membrane
5. no cytoplasm
6. no vacuole
7. no plasmids
8. no flagella(flagellum
Flowers are
