biology - mocks

Give five uses of energy

Chemical reactions, muscle contraction, maintaining temperature, cell division and growth, active transport, protein synthesis

Is cellular respiration exothermic or endothermic?

Exothermic

What does cellular respiration do?

Releases energy from glucose

What is energy transferred by?

Adenosine Triphosphate

Define aerobic respiration

The chemical reaction in cells that uses oxygen to break down nutrient molecules to release energy

What is aerobic respiration?

Complete breakdown of glucose to release a large amount of energy

Give the word equation for aerobic respiration

Glucose + oxygen -> carbon dioxide + water

Give the balanced equation for aerobic respiration

C6H12O6 + 6O2 -> 6CO2 + 6H2O

Define anaerobic respiration

The chemical reaction in cells that breaks down nutrient molecules to release energy without using oxygen

What is anaerobic respiration?

The incomplete breakdown of glucose to release a small amount of energy

Give the word equation for anaerobic respiration in animals

Glucose -> lactic acid

Give the balanced equation for anaerobic respiration in animals

C6H12O6 -? 2C3H6O3

Why is long-term anaerobic respiration bad?

Lactic acid builds up in muscle cells and lowers the pH of the muscle tissue, which can denature enzymes.

How is lactic acid broken down?

Using oxygen to produce carbon dioxide and water

Give the word equation for anaerobic respiration in plants and fungi

Glucose -> ethanol + carbon dioxide

Give the balanced equation for anaerobic respiration in plants and yeast

C6H12O6 -> 2C2H5OH + 2CO2

Give the hydrogen carbonate colours and CO2 levels

Yellow - high CO2

Orange - atmospheric

Purple - low

How could plants producing CO2 be proved?

Hydrogen carbonate indicator, germinating seeds, dead boiled seeds, glass beads. Colour change.

Explain four features of the lungs which enable gas exchange

Large surface area - faster diffusion of gases across surface.

Thin walls - short diffusion distances

Good ventilation - maintains diffusion gradients

Good blood supply - maintains high concentration gradient

Describe the function of the ribs

Bone structure that protects internal organs

Describe the function of the intercostal muscle

Muscles between ribs which control movement causing inhalation and exhalation

Describe the function of the diaphragm

Sheet of connective tissue and muscle at the bottom of the thorax that helps change the volume of the thorax to allow inhalation and exhalation

Describe the function of the trachea

Windpipe that connects the mouth and nose to the lungs

Describe the function of the larynx

Voice box

Describe the function of the bronchi

Large tubes branching off the trachea with one bronchus for each lung

Describe the function of the bronchioles

Bronchi split to form smaller tubes called bronchioles in the lungs connected to alveoli

Describe the function of the alveoli

Tiny air sacs where gas exchange takes place

Describe the function of the pleural cavity

Fluid filled space between pleural membranes which reduces friction and allows lungs to move freely

What are the passages down to the lungs lined with?

Ciliated epithelial cells

What do ciliated epithelial cells do?

Cilia beat to push mucus made by goblet cells that trap particles towards nose and throat to be removed.

Give four features of alveoli which make them highly specialised for gas exchange

Many rounded alveolar sacs which give a very large surface area to volume ratio.

Alveoli and capillaries have thin, single layers of cells to minimise diffusion distance.

Good blood supply maintains high carbon dioxide and low oxygen levels for diffusion gradients.

Layer of moisture on the surface of the alveoli helps diffusion as gases dissolve.

What do external intercostal muscles do?

Pull the ribcage up and out

What do internal intercostal muscles do?

Pull the ribcage down and in

Give the five steps of inhalation

Diaphragm contracts and flattens. External intercostal muscles contract, pulling ribs up and out. Volume of chest cavity increases. Air pressure in lungs decreases relative to outside. Air is drawn in.

Give the five steps of exhalation.

Diaphragm relaxes. External intercostal muscles relax, dropping ribs down and in. Volume of chest cavity decreases. Air pressure in lungs increases relative to outside. Air is forced out.

What are the percentages of oxygen in inspired and expired air?

21% inspired, 16% expired

What are the percentages of carbon dioxide in inspired and expired air?

0.04% inspired, 4% expired

What are the percentages of nitrogen in inspired and expired air?

78% inspired, 78% expired

What two conditions does smoking cause?

Chronic obstructive lung disease and coronary heart disease

What does smoking increase the risk of?

Cancer

Give three chemicals in cigarettes

Tar, nicotine, and carbon monoxide

Describe the effects of nicotine

Narrows blood vessels leading to increased blood pressure and increases heart rate, both of which can cause blood clots to form in arteries, leading to heart attacks or strokes.

Describe the effects of carbon monoxide

Binds irreversibly to haemoglobin, reducing the capacity of blood to carry oxygen, putting more strain on breathing system as frequency and depth needs to increase in order to get same amount of oxygen into blood. Also puts more strain on circulatory system to pump blood faster around the body and increases risk of coronary heart disease and strokes.

Describe the effects of tar

Carcinogen increasing chances of cancerous cells developing in lungs. Contributes to COPD, which occurs when chronic bronchitis and emphysema occur together. CB is caused by tar which stimulates goblet cells, producing more mucus. It destroys cilia, causing mucus build up, blocking bronchioles and leading to infections. Emphysema develops as a result of frequent infection. Phagocytes that enter lungs release elastase, an enzyme that breaks down elastic fibres in alveoli. Alveoli become less elastic, so many burst, reducing surface area for gas exchange.

What does blood consist of, in order of make up?

Plasma, red blood cells, white blood cells and platelets

Define red blood cells

Biconcave discs with no nucleus and lots of the protein haemoglobin

What are platelets

Fragments of cells

What is plasma?

Straw coloured liquid

Give the three features of RBCs that make them specialised to carry oxygen

Full of haemoglobin. No nucleus - more room for haemoglobin. Biconcave disc - large surface area to volume ratio.

Give three things that plasma transports

Carbon dioxide, urea, hormones

What is the function of platelets?

Helps blood clot, releasing chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin, forming an insoluble mesh across the wound, trapping RBCs and forming a clot.

Why is blood clotting important?

Prevents continued blood loss and prevents entry of microorganisms that could cause infection

Give the two types of WBC

Phagocytes and lymphocytes

Describe the process of phagocytosis

Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells. On encountering a pathogenic cell, they will engulf it and release digestive enzymes to digest it. This is a non-specific immune response.

What do lymphocytes do?

Produce antibodies which are complementary to antigens of the surface of the pathogen. Antibodies attach to antigens and cause agglutination, preventing the pathogenic cells from moving easily. At the same time, chemicals are released that signal to phagocytes that there are cells present that need to be destroyed. This is a specific immune response. Lymphocytes also produce antitoxins to neutralise toxins released by pathogens.

Describe the stages of infection and immune response

The pathogen enters the blood stream and multiplies

A release of toxins (in the case of bacteria) and infection of body cells causes symptoms in the patient

Phagocytes that encounter the pathogen recognise that it is an invading pathogen and engulf and digest (non-specific response)

Eventually, the pathogen encounters a lymphocyte which recognises its antigens

The lymphocyte starts to produce specific antibodies to combat that particular pathogen

The lymphocyte also clones itself to produce lots of lymphocytes (all producing the specific antibody required)

Antibodies cause agglutination of pathogens

Phagocytes engulf and digest the agglutinated pathogens

After the patient has recovered, they retain antibodies specific to the disease as well as memory cells (lymphocytes that recognise the pathogen)

If the patient encounters the same pathogen again, it will trigger a secondary immune response

Memory cells can produce much larger quantities of the required antibody in a much shorter time to fight off the pathogen before the patient suffers any symptoms

How do vaccines work?

Harmless versions of pathogens are injected, and the body responds eventually producing memory cells, giving long-term immunity. Future infection by the same pathogen will trigger a response that is much faster and larger than the initial response.

Give two benefits of vaccination

Reduced likelihood that infected individual will spread pathogen to others. Eradication of disease.

Give two disadvantages of vaccinations

Mutations in the pathogen's D/RNA can result in changes to the antigen, meaning that lymphocytes no longer recognise the pathogen. Side-effects of vaccination can reduce uptake in population.

Explain how the passage of blood through the heart works

Oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body. The left ventricle has a thicker muscle wall as it has to pump blood at a high pressure around the entire body. Deoxygenated blood from the body enters the right side of the heart and is pumped to the lungs. A muscle wall called the septum separates the two sides.

What is blood pumped towards the heart in?

Veins

What is blood pumped away from the heart in?

Arteries

What do coronary arteries do?

Supply cardiac muscle tissue with oxygenated blood

What do valves do?

Prevent backflow of blood

Describe the pathway of blood through the heart

Deoxygenated blood coming from the body flows through the vena cava and into the right atrium

The atrium contracts and the blood is forced through the tricuspid (atrioventricular) valve into the right ventricle

The ventricle contracts and the blood is pushed through the semilunar valve into the pulmonary artery

The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place

Low pressure blood flow on this side of the heart prevents damage to the capillaries in the lungs

Oxygenated blood returns via the pulmonary vein to the left atrium

The atrium contracts and forces the blood through the bicuspid (atrioventricular) valve into the left ventricle

The ventricle contracts and the blood is forced through the semilunar valve and out through the aorta

Thicker muscle walls of the left ventricle produce a high enough pressure for the blood to travel around the whole body

Give two sources of cholesterol

Dietary cholesterol and cholesterol synthesised by the liver

CHD results in blockage of coronary arteries. What does a partial blockage cause?

Restricts blood flow to cardiac muscle cells, resulting in severe chest pains called angina

CHD results in blockage of coronary arteries. What does a complete blockage cause?

Cells in that area of the heart cannot respire aerobically, leading to a heart attack

How is CHD treated?

Increasing the width of the lumen using a stent, or prescribing statins to lower blood cholesterol

Give four risk factors of coronary heart disease

Obesity, high blood pressure, high cholesterol, smoking

Give the three types of blood vessel

Arteries, veins, capillaries

Give four key features of arteries

Carry blood at high pressure and speed away from heart. Carry oxygenated blood (except pulmonary artery). Thick muscular walls. Narrow lumen.

Give five features of veins

Carry blood at low pressure and speed towards heart. Carry deoxygenated blood (except pulmonary vein). Thin walls. Large lumen. Contain valves.

Give four features of capillaries

Carry blood at low pressure and speed within tissues. Carry both oxygenated and deoxygenated blood. Walls are one cell thick. Plasma can leak out and form tissue fluid surrounding cells.