Respiration and gas Exchange

Question 1

Uses of energy in the body of humans:

Answer 1

• Muscle contraction: Contracting muscle so we can move parts of the body.
• Protein synthesis: Make protein molecules by linking them together with amino acids into long chains
• Cell division: So that we can repair damaged tissues and can grow
• Active transport: So that we can move substances across cell membranes up they concentration gradients
• Growth
• Passage of nerve impulses: Transmitting nerve impulses, so that we can transfer information quickly from one part of the body to another.
• Maintenance of a constant body temperature: Producing heat inside the body, to keep the body temperature constant even if the environment is cold.

Question 2

Aerobic respiration

Answer 2

the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

Question 3

Word equation for aerobic respiration

Answer 3

glucose + oxygen → carbon dioxide + water

Question 4

balanced chemical equation for aerobic respiration

Answer 4

C6H12O6 + 6O2 → 6CO2 + 6H2O

Question 5

Investigate effect of temperature on the rate of respiration of germinating seeds

Answer 5

Set up:
Germinating seeds are placed in a boiling tube on a wire gauze. Soda lime is placed at the bottom (to absorb CO2) and the boiling tube is placed in a water bath of a known temperature.
A capillary tube is connected to the boiling tube, with colored dye introduced. The initial position of the dye is measured against a ruler and as the seeds respire, the dye will move towards the boiling tube.
-Rate of respiration = distance travelled by dye/ time taken
-Prediction to experiment: As temperature increases, respiration rate will increase, and then decrease.
-Explanation: As there is an optimum temperature at which seeds germinate, At high temperatures the enzymes will denature, and at low temperature there is not enough kinetic energy fro effective collisions.

Question 6

Investigate the uptake of oxygen by respiring organisms, such as arthropods and germinating seeds

Answer 6

A simple respirometer is used. An organism is placed in the boiling tube on top of the wire gauze. A capillary tube connected to the boiling tube is measured against a ruler, and a colored dye is introduced into it.

With the starting point of the dye measured, the dye will move towards the boiling tube as the organism uses up the oxygen in the air.

The carbon dioxide produced by the organism is eliminated/absorbed by the soda lime, and therefore does will affect the dye position.

We can measure the rate of respiration by calculating the distance traveled by the dye and dividing it by the time it took.

Question 7

Anaerobic respiration

Answer 7

the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen

Question 8

word equations for anaerobic respiration in muscles during vigorous exercise and
the microorganism yeast

Answer 8

• glucose → lactic acid

- glucose → alcohol + carbon dioxide

Question 9

balanced chemical equation for anaerobic respiration in the microorganism yeast

Answer 9

C6H12O6 → 2C2H5OH + 2CO2

Question 10

Energy released from anaerobic respiration and aerobic respiration

Answer 10

anaerobic respiration releases much less energy per glucose molecule than aerobic respiration

Question 11

How oxygen debt is caused

Answer 11

lactic acid builds up in muscles and blood during vigorous exercise causing an oxygen debt

Question 12

How the oxygen debt is removed during recovery

Answer 12

-aerobic respiration of lactic acid in the liver
– continuation, after exercise, of fast heart rate to transport lactic acid in blood from muscles to the liver
– continuation, after exercise, of deeper breathing supplying oxygen for aerobic respiration of lactic acid

Question 13

features of gas exchange surfaces in humans

Answer 13

• Large surface area: So that alot of case can diffuse across at the same time
• Thin surface: Allow gases to diffuse across them quickly
• Close to efficient transport system to take gases to and from the exchange surfaces
• They have good supply of oxygen (brought by breathing movements)

Question 14

Name and identify the lungs, diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries

Answer 14

In textbook

Question 15

Name and identify the internal and external intercostal muscles

Answer 15

Intercostal muscles are found between the ribs, Internal and external intercostal muscles work antagonistically to expand and contact the rib cage during breathing

Question 16

Functions of the cartilage in the trachea

Answer 16

They provide structural strength, keeping the trachea open so air can pass through it.

Question 17

role of the ribs, the internal and external intercostal muscles and the diaphragm in producing volume and pressure changes in the thorax leading to the ventilation of the lungs

Answer 17

• Breathing in (inspiration) internal Intercostal muscles relax whilst external intercostal muscles contract, pulling the ribs up and out while the diaphragm flattens, pushing the abdominal muscles downwards. The volume in thorax increases, so sir enters the lungs by diffusion as volume of thorax increases there is a low concentration of air inside lungs compared to outside, thus air diffuses in.
• Breathing out (Expiration): Volume of thorax decreases, increasing pressure so that air is forced out. This is passive (does dont require muscles contraction) except when forcefully breathing out, where the internal intercostal muscles contract.

Question 18

differences in composition between inspired and expired air

Answer 18

Majority of atmosphere air is nitrogen, oxygen and CO2, Inhaled air made up of more oxygen than exhaled air since oxygen is absorbed into the blood in the alveoli instead of being exhaled. oxygen is used in cells for respiration, and carbon dioxide is produced as waste product. CO2 released from the blood at alveoli and diffuses out into lungs before exhaled. Exhaled air contains more water vapor than exhaled air.

Question 19

Limewater as a test for carbon dioxide to investigate the differences in composition between inspired and expired air

Answer 19

To investigate the differences in composition between inspired and expired air, we use limewater because it change colour when the gas is bubbled through, from colourless to milky. There is more CO2 present in expired air —> it makes limewater change colour more quickly (than inspired air).

Question 20

Effects of physical activity on rate and depth of breathing

Answer 20

-During physical excercise rate and depth of breathing increases. Muscles increase the rate of respiration to produce energy for muscle contraction.
-Aerobic respiration demands more oxygen, thus a greater amount of CO2 is produced as a waste product,
which diffuses in the blood, this increases CO2 in the blood, detected by the brain it causes rate of breathing to speed up. Allowing gas exchange to happen rapidly, removing CO2 and taking in more Oxygen. heart rate is also increased to pump substances around the body quickly.

Question 21

role of goblet cells, mucus and ciliated cells in protecting the gas exchange system from pathogens and particles

Answer 21

-lungs are adapted to protect from foreign pathogens and particles. Goblet cells found in trachea and bronchi, adapted to secrete mucus into respiratory tract. Foreign pathogens and particles stick to mucus, moved upwards towards throat by cilia. Mucus is swallowed and pathogens are destroyed in stomach in the acidic conditions.