Cells
What is the control centre of a cell?
A: Nucleus
: Which gas is taken in during photosynthesis?
A: Carbon dioxide
What type of bonding is found in magnesium oxide?
A: Ionic bonding
What is made when an acid reacts with a metal?
A: A salt and hydrogen gas
What is homeostasis?
A: Maintaining a constant internal environment.
Which cell structure is the site of aerobic respiration?
A: Mitochondria
Write the word equation for photosynthesis.
A: Carbon dioxide + water → glucose + oxygen
What are the charged particles in an ionic compound called?
A: Ions
A: Ions
What is the pH of a neutral solution?
7
Which hormone lowers blood glucose concentration?
A: Insulin
Name the blood vessel that carries oxygenated blood from the lungs to the heart.
A: Pulmonary vein
Name one factor that can limit the rate of photosynthesis.
A: Light intensity, carbon dioxide concentration or temperature
Why do metals conduct electricity?
A: They contain delocalised electrons that can move through the metal.
Why is aluminium extracted by electrolysis instead of using carbon?
A: Aluminium is more reactive than carbon.
Which hormone prepares the body for 'fight or flight'?
A: Adrenaline
Why are villi found in the small intestine?
A: To increase the surface area for absorption of digested food.
What is the purpose of respiration in living cells?
A: To release energy from glucose.
Why does diamond have a very high melting point?
A: It has many strong covalent bonds in a giant covalent structure, requiring lots of energy to break.
During electrolysis of molten lead bromide, what is produced at the positive electrode?
A: Bromine
Explain how insulin lowers blood glucose concentration.
A: It causes glucose to move from the blood into cells and stimulates the liver and muscles to store glucose as glycogen.
Explain two ways red blood cells are adapted to carry oxygen.
A: They have a biconcave shape (large surface area) and contain haemoglobin. They also have no nucleus, leaving more room for haemoglobin.
Explain why plants respire all the time but only photosynthesise during daylight.
A: Respiration happens continuously to release energy, but photosynthesis requires light, so it only happens when there is enough light.
Compare the properties of diamond and graphite, explaining why they are different.
A: Diamond is very hard and does not conduct electricity because each carbon atom forms four bonds. Graphite is soft and conducts electricity because each carbon atom forms three bonds, leaving one delocalised electron.
Explain why electrolysis is more expensive than extracting iron in a blast furnace.
A: Electrolysis uses a large amount of electricity, making it more expensive.
A person's blood glucose concentration rises after eating a meal. Explain how the body returns it to normal.
A: The pancreas detects the increase and releases insulin. Cells take up more glucose and the liver converts excess glucose to glycogen. Blood glucose concentration then returns to normal through negative feedback.