Unit 1 - Biology: Cells, energy and circulation

Question 1

Define Diffusion

Answer 1

DIffusion is the net movement of molecules from a region of higher concentration to a region of their concentration down a concentration gradient, as a result of their random movement.

Question 2

Describe the importance of diffusion of gases and solutes and of water as a solvent

Answer 2

Solutes will diffuse out in water, making a solution because the particles will move to places where it is less concentrated until the solution is uniformly concentrated.

Question 3

Define “enzymes”

Answer 3

Enzymes are proteins that function as biological catalysts

Question 4

Investigate and describe the effect of changes in temperature and pH on enzyme activity

Answer 4

Enzymes are proteins and consist of very large molecules. These molecules have special shapes which are important to their ability to act as catalysts. If enzymes are heated above 45°C, their molecules lose their shapes, and so they don’t work well as catalysts at higher temperatures.

Extremely high or low pH levels generally result in complete loss of activity for most enzymes.

There are optimum pH levels and temperature for each kind of enzyme.

Question 5

Define photosynthesis

Answer 5

The process by which plants manufacture carbohydrates from raw materials using energy from light

Question 6

Function of chlorophyll

Answer 6

Traps light energy and converts it into chemical energy for the formation of carbohydrates and their subsequent storage

Question 7

Word and balanced equation for photosynthesis

Answer 7

Carbon dioxide + water (+ energy) in the presence of sunlight and chlorophyll -> glucose + oxygen

6CO2 + 6H2O -> C6H12O6 + 6O2

Question 8

Describe the circulatory system

Answer 8

A system of tubes with a pump and valves to ensure one-way flow of blood.

Question 9

Describe Double circulation

Answer 9

A low pressure circulation to the lungs and a high pressure circulation to the body tissues.

The circulation to the lungs carry deoxygenated blood from the pulmonary artery. The high pressured circulation carries blood from heart to everywhere in the body.
The pulmonary veins carry oxygenated blood from the lungs to the heart.

When blood is transported from the heart to the lungs, the pressure it travels at is relatively smaller than the second circuit, where the blood is transported from the heart to the rest of the body.

Question 10

Define respiration

Answer 10

The chemical reactions that break down nutrient molecules in living cells to release energy.

Question 11

State the uses of energy in the body of humans

Answer 11

Muscle contraction, protein synthesis, cell division, growth, the passage of nerve impulses and the maintenance of a constant body temperature.

Question 12

Define aerobic respiration

Answer 12

The release of a relatively large amount of energy in cells by the breakdown of food

Question 13

Word equation and balanced equation for aerobic respiration

Answer 13

Glucose + oxygen -> carbon dioxide + water + energy

C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy

Question 14

Define digestion

Answer 14

The breakdown of large, insoluble food molecules into small, water soluble molecules using mechanical and chemical processes.

Question 15

Define absorption

Answer 15

Movement of digested food molecules through the wall of the intestine into the blood.

Question 16

List the components of blood

Answer 16

Red blood cells
White blood cells
Platelets
Plasma

Question 17

State the functions of the following components of blood:

• Red blood cells
• White blood cells
• Platelets
• Plasma

Answer 17

Red blood cells: Haemoglobin and oxygen transport. Bi-concave discs = large surface area to carry more oxygen/deoxygen. Transport O2 and CO2

White blood cells: Phagocytosis and antibody formation. To kill invading bacteria/viruses

Platelets: Causing clotting (of wounds)

Plasma: transport of blood cells, ions, soluble nutrients, hormones and carbon dioxide.

Question 18

Investigate the necessity for chlorophyll, light and carbon dioxide for photosynthesis, using appropriate controls

Answer 18

Without enough light, a plant cannot photosynthesis very quickly, even if there is plenty of water and carbon dioxide. In the process of photosynthesis, plants use chlorophyll to convert carbon dioxide and water into glucose and oxygen. The glucose is joined together in long chains of starch molecules, the oxygen is released into the air.

A variegated plant is used to test for the relationship between the green pigment in plants & starch production.
1. A destarched variegated plant was left in the sunlight for four hours.
2. A leaf is removed and tested for starch.
The green parts of the leaf contain starch.
The white do not.
3. This suggests that chlorophyll is needed for starch production.

Showing how light is needed to make starch.
1. Two leaves of a de-starched plant are to be tested for the presence of starch.

2. One is completely covered with aluminium foil, the other with clear plastic wrap.
3. The plant is put in the sun for 4 hours, and both leaves are tested for starch.

The leaf in the plastic contains starch.
The leaf in the foil does not.

This suggests that light is needed for the production of starch.

Experiment for Carbon dioxide
Destarch a potted geranium plant by leaving it in a dark cupboard for three days. Test a leaf for the presence of starch. None may be present. Place a leaf in a conical flask with a 100 cm3 of sodium hydroxide solution to absorb the carbon dioxide from the air in the flask. Close the flask with a split stopper with an opening for the leaf stalk. Seal the cork and the split in the stopper with petroleum jelly. Clamp the flask at an angle in a retort stand so the leaf does not touch the sodium hydroxide solution.

Method (control)

Place another leaf from the plant in another conical flask with sodium bicarbonate - which releases carbon dioxide into the flask. Close and seal in the same way as for the experiment. Clamp in position securely. Mark each flask clearly. Leave apparatus in a sunny spot for a few hours. Remove the leaves and carry out the starch test.

Result

The leaf in the experiment did not have starch, while that of the control did.

Question 19

Investigate and state the effect of varying light intensity on the rate of photosynthesis (eg in submerged aquatic plants)

Answer 19

In bright light, the rate of photosynthesis increases in temperature up to a maximum of 40°C. Beyond this maximum temperature, the rate of photosynthesis drops rapidly.

A water plant such as Elodea pond weed or Cabomba pond weed is placed upside in a test tube containing water. The pond weed is weighted down with a paperclip to ensure it remains fixed in position. The test tube is placed in a beaker containing water. This so the large volume of water in the beaker maintains a constant temperature around the pond weed. The light source is provided by a lamp and light intensity is measured by the distance of the lamp in relation to the pond weed.

With light present the pond weed undertakes photosynthesis and gives of oxygen gas which can be seen as bubbles. By counting the number of bubbles given of in a fixed time period for e.g one minute the rate of photosynthesis can be determined. At the start of the experiment the lamp is positioned 1m from the pond weed and the number of gas bubbles produced is recorded. The lamp is then brought closer to the pond weed and the respective distance and number of bubbles recorded.

In this experiment a 100 Watt bulb was used. As the bulb emits light in all direction we use the area of a sphere with the radius being the distance from the pond weed. The number of bubbles given off in a minute is taken as the rate of photosynthesis and plotted against the calculated light intensity. From the graph it can be seen that the rate of photosynthesis increase with light intensity to a point until the other factors such as carbon dioxide and temperature become the limiting factors.

Question 20

Describe the intake of carbon dioxide and water by plants

Answer 20

Root hair cell
Plants absorb water from the soil by osmosis. Root hair cells are adapted for this by having a large surface area to speed up osmosis.
The absorbed water is transported through the roots to the rest of the plant where it’s used for different purposes:
It’s a reactant used in photosynthesis
It supports leaves and shoots by keeping the cells rigid
It cools the leaves by evaporation
It transports dissolved minerals around the plant

Leaves
Leaves are adapted for photosynthesis by having a large surface area, and contain stomata (openings) to allow carbon dioxide into the leaf. These design features can result in the leaf losing a lot of water. The cells inside the leaf have water on their surface. Some of this water evaporates, and the water vapour can then escape from inside the leaf by diffusion.
To reduce loss the leaf is coated in a wax cuticle to stop the water vapour escaping through the epidermis. Leaves usually have fewer stomata on their top surface to reduce this water loss.

Question 21

Identify and label the cuticle, cellular and tissue structure of a dicotyledonous leaf, as seen in cross section under the light microscope.

Answer 21

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Question 22

State what is meant by the term balanced diet and describe a balanced diet related to age, sex and activity of an individual.

Answer 22

Balanced diet: A balanced diet is a diet which consists of all nutrients in the food pyramid to suitable proportions. (FOOD PYRAMID)

Carbs for energy
Fats for energy and warmth
Protein for muscles
Fibre for digestion

Question 23

Describe the effects of malnutrition in relation to starvation, coronary heart disease, constipation and obesity

Answer 23

Malnutrition is a condition where certain nutrients of a balanced diet are missing, in excess, or taken in the wrong proportions.

Starvation occurs when a person has a severe deficiency of energy, nutrient and vitamin intake. Prolonged starvation may cause organ damage, and if not treated properly, death.

Coronary heart disease: speaking in terms of diet, is caused by an over-abundance of intake of fatty foods, and what happens is that the cholesterol and “bad” things deposit and eventually form a clog in the arteries, hence preventing proper blood flow in the body. When your heart’s blood supply is blocked or interrupted by a build-up of fatty substances in the coronary arteries. Can cause heart attacks, chest pain and heart failure.

Constipation: Bowel movements are obstructed and one cannot poop. It can mean that you are not passing stools (poo) regularly, or you are unable to completely empty your bowels.
Constipation can also cause your stools to be hard, lumpy, large or small. Not getting enough fibre in your diet or water.

Obesity: An over-abundance of calorie intake, increased dependence on fast food and sugary foods have accelerated the number of obese people. A person is considered obese if his/her body weight is 20%above the standard body weight. High blood pressure, diabetes, heart disease.

Question 24

Identify the main regions of the alimentary canal and associated organs including mouth, salivary glands, oesophagus, stomach, small intestine (duodenum and ileum), pancreas, liver, gall bladder, large intestine (colon and rectum), anus.

Answer 24

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Question 25

Describe the functions of the regions of the alimentary canal (mouth, salivary glands, oesophagus, stomach, small intestine (duodenum and ileum), pancreas, liver, gall bladder, large intestine (colon and rectum), anus) in relation to ingestion, digestion, absorption, assimilation and egestion of food.

Answer 25

Mouth: where food enters. Ingestion. Also digestion.

Salivary glands: amylase secretion, which breaks down starch into maltose, so the substance can be more easily digested. Digestion

Oesophagus: the food is now in a small round mass and travels down the oesophagus by peristalsis. Digestion

Stomach: gastric juices in stomach starts digesting the proteins.

Small intestine: a thick liquid called chyme is produced.

Pancreas: The chyme enters the duodenum, and is mixed with digestive enzymes in the pancreas. Eventually, this is passed down the small intestines. Chyme is absorbed into blood when digested. Pancreas makes pancreatic juice. This secretes important enzymes for digestion such as amylase, pancreatic lipase, and forms of proteases. ABSORPTION

Liver: The liver produces bile, which emulsifies (mixture of two or more liquids) fats, to allow absorption. Bile is stored in the gallbladder where it is then released to small intestine via bile duct.

Gall bladder: holds bile produced in the liver until it is needed for digesting fatty foods in the duodenum of the small intestine.

Large intestine: water and minerals are reabsorbed into the blood in the colon. ABSORPTION.

Anus: Stored feces are eliminated from the body through the anus, via the process egestion.

Question 26

Identify the types of human teeth and describe their structure and functions.

Answer 26

Enamel: Covers tooth crown. Enamel is VERY hard (harder than bone), and prevents the tooth from decaying.
Dentin: Located under the enamel, this looks quite similar to bone. Not as hard as enamel.
Pulp: Found at centre of tooth, and contains blood vessels, nerves and soft tissues which delivers nutrients to your tooth.

Incisors: thin profile = small surface area = large pressure = cutting. To bite into food.

Canine: For ripping and tearing food. Sharp.

Premolar: Chewing and grinding. Relatively flat top = greater area for grinding.

Molar: chewing and grinding. Big. Relatively flat top = greater area for grinding.

Question 27

State the causes of dental decay and describe the proper care of teeth.

Answer 27

Causes of dental decay:

• Tooth decay is caused by a combination of bacteria and food.
• A sticky substance called plaque which contains bacteria is constantly being formed in your teeth.
• When bacteria feed on the sugars you eat, it forms acids.
• Over a prolonged period of time, the acids starting destroying the tooth enamel, hence causing tooth decay.

Treatment:

• Brush teeth frequently
• Fillings (filling in the gaps and crevasses so bacteria doesn’t live down there.)
• eat less sugary foods
• regular dental appointments

Question 28

State the significance of chemical digestion in the alimentary canal

Answer 28

Producing small, soluble molecules that can be absorbed.

Question 29

Where is the region for the absorption of digested food.

Answer 29

Small intestine.

Assimilation happens in tissues. Or whereever needed

Question 30

Identify on diagrams and name the larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries.

Answer 30

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Question 31

List the features of gas exchange surfaces in animals.

Answer 31

Gas exchange surfaces are, in essence, organs that allow the diffusion of gas in and out of the body. For mammals, that would be the lungs. More specifically, gas exchange takes place in the alveoli.

There are several key features of gaseous exchange in humans:

• The walls of the alveoli are made from a single layer of cells – allows for gases to easily diffuse in and out of the capillaries.
• The alveoli have a moist lining – The oxygen dissolves into the moist lining and enters the blood stream.
• Large surface area – The lungs contain a lot of alveoli, allowing for more gas to be exchanged.

Question 32

Explain the role of mucus and cilia in protecting the gas exchange system from pathogens and particles.

Answer 32

The bronchi in the lungs are lined with cilia cells. They are the cells that line the lungs with hair-like protrusions. They move in a wave-like motion, sweeping the mucus upwards. The cilia cells sweep any unwanted microbes or particles out of our lungs and airways.

Goblet cells line the tubes leading to the lungs. They keep the lungs clean by making mucus. The mucus covers the inside of the trachea. Dust and bacteria get trapped in the mucus. Cilia then sweep the mucus to the back of the throat to be swallow and the dirt and bacteria are then destroyed in the digestive system.

Question 33

Describe the effects of tobacco smoke and its major toxic components (tar, nicotine, carbon monoxide, smoke particles) on the gas exchange system

Answer 33

Cigarette smoke contains carbon dioxide and carbon monoxide. These substances stop the cilia from moving. IF a person smokes a lot, their cilia will disappear completely.
-The goblet cells go on working. They still make mucus, and the mucus still traps dirt and bacteria. But the mucus is not swept upwards. It trickles downwards, into the lungs. The lungs now start to fill up with mucus, bacteria and smoke particles.

Tar:
The presence of tar in our airways causes more mucus to be produced by the goblet cells. In addition, tar also paralyzes our cilia cells, meaning that they cannot properly function and remove the mucus. The result is that excess mucus builds up in our airways. Smokers cough more often to shift the mucus to the back of their throats.

The tar also clogs up the alveoli in our lungs, reducing the surface area for gas exchange to take place, therefore resulting in less oxygen entering your body.

Tar is also a carcinogen, a substance that increases the risk of cancer. The deposited tar in our lungs raises the risk of lung cancer amongst other diseases such as chronic bronchitis.

Nicotine:
The presence of nicotine in our bloodstream raises our hearts’ beat per minute, in addition to increases blood [pressure by narrowing our blood vessels.

Carbon monoxide:
The carbon monoxide binds with the haemoglobins in our red blood cells, reducing its ability to carry oxygen around our body. As a result, it puts more strain our body’s respiratory system.

Smoke particles:
The smoke particles may also coat the walls of the alveoli, preventing gas exchange from taking place.

Question 34

State the differences in composition between inspired and expired air.

Answer 34

Inspired air - the air you breathe in
Expired air - the air you breathe out

Exhaled air has high levels of CO2 and water vapour while inhaled air has O2 and very little amount or no water vapour.

Inspired air has around 21% of oxygen whilst expired air consists of 17% oxygen.

Question 35

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

Answer 35

Use a bung thingy diagram in folder.

We can use lime water to investigate the difference between inspired and expired air.

Lime water, in the presence of carbon dioxide becomes cloudy.

In ambient air, lime water is clear because the ambient air does not contain a significant amount of carbon dioxide.

However, if you breathe into a solution of lime water, it turns cloudy/milky as the lime water absorbs the carbon dioxide.

Question 36

Investigate and describe the effects of physical activity on rate and depth of breathing

Answer 36

Exercise and other intense physical activity will increase our rate of breathing, in addition to shortening the depth of our breath.

Question 37

Explain the effects of physical activity on rate and depth of breathing

Answer 37

During exercise, the muscle cells respire more than they do at rest. This means that:

• Oxygen and glucose must be delivered to them more quickly
• Waste carbon dioxide must be removed more quickly.

The increased heart rate increases the rate of blood flow around the body. The increased rate and depth of breathing increases the rate of gaseous exchange in the lungs.
The muscles store glucose as glycogen. This can then be converted back to glucose for use during exercise.

When cells become more active, such as our muscles when we exercise, they need more oxygen in order to perform aerobic respiration to break down glucose and release energy. As a result, we breath faster in order to deliver more oxygen to cells around our body.

Question 38

Describe the structure of the heart including the muscular wall and septum, atria, ventricles and valves and associated blood vessels.

Answer 38

The heart has four chambers, two atria and two ventricles.

The sides of the heart are separated by the septum. Each side of the heart contains an atrium and a ventricle, atrium at the top, ventricle on the bottom, and there is a Valve between the atrium and ventricle of each side. On the left, the valve is called the Bicuspid valve, and on the right, the Tricuspid valve.

There are four major blood vessels associated with the heart:

Pulmonary Veins: This transports oxygenated blood from the lungs to the left atrium
Aorta: This transports oxygenated blood from the heart to the rest of the body and the brain.
Vena Cava: This transports deoxygenated blood from the rest of the body to the heart.
Pulmonary Artery: Transports deoxygenated blood to the heart to the lungs.

Question 39

Describe the function of the heart in terms of muscular contraction and the working of the valves

Answer 39

When the heart is being filled with blood, we call this Diastole. When the heart is pumping blood out, we call this Systole.

During Diastole, the blood first enters the atria, the atria contracts for force blood into the ventricles, both the tricuspid and bicuspid valves are opened to allow blood into the ventricles. The semi-lunar, however, is shut.

Once the ventricles are filled with blood, Systole happens. The bicuspid and tricuspid valves shut and semi-lunar valves open. The ventricles contract to force blood into the aorta and pulmonary arteries.

During diastole, the semi-lunar valves are shut to keep the blood out of the arteries. However, during systole, the tricuspid and bicuspid valves are closed to prevent blood from flowing back into the atria when it opens. The tricuspid and bicuspid valves are made out of tendons, and then prevent blood from following backwards and make sure blood flows only in one direction.

The heart is a muscular pump. When it beats it pumps blood to the lungs and around the body.

Question 40

Investigate, state and explain the effect of physical activity on pulse rate.

Answer 40

Physical activity increases pulse rate. During exercise, the muscle cells respire more than they do at rest. This means that:

• Oxygen and glucose must be delivered to them more quickly
• Waste carbon dioxide must be removed more quickly

The increased heart rate increases the rate of blood flow around the body.

Question 41

Identify red and white blood cells as seen under the light microscope on prepared slides, and in diagrams and photomicrographs.

Answer 41

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Question 42

Describe coronary heart disease and state the possible causes and preventive measures

Answer 42

Blockage of coronary arteries.
Coronary Heart Disease is a heart disease where certain parts of the “coronary artery” becomes “clogged” with cholesterol , and substances such as oxygen and nutrients cannot be transported across the body.

If not properly treated, a blood clot may form near the partially “clogged” area, completely blocking the artery. No oxygen or nutrients is able to be transported around the body, little/no respiration is able to occur, that part of the heart dies, and the victim gets a heart attack, which is extremely fatal.

Possible Causes of Coronary Heart Disease

• Lack of exercise
• Diet high in fat and cholesterol
• Diabetes
• High Blood Pressure
• Genetics
• Stress
• Smoking

Preventive measures

• exercise regularly
• healthy diet
• don’t smoke