After ovulation, progesterone rises. Later in a cycle with no pregnancy, progesterone falls.
.1
Explain the effect of progesterone while its concentration is high.
[2 marks].2
Explain what follows the fall in progesterone.
[2 marks]OCR Gateway GCSE Combined Science June 2019 Paper 7
5 questions on this paper's topics
25:001 of 5
Oxygen volumes collected from pondweed in three 5-minute repeats are 4.5, 5.0 and 5.5 cm³. A second student counts bubbles instead of collecting gas.
.1
Calculate the mean oxygen production rate.
[2 marks].2
Evaluate counting bubbles compared with collecting gas volume.
[2 marks]Two neurones meet at a synapse. An electrical impulse reaches the end of the first neurone.
.1
Describe how information passes to the second neurone.
[3 marks].2
A substance stops release of the chemical. Predict the effect on transmission at this synapse and explain your answer.
[1 mark]A potometer reservoir initially contains 24.0 cm³ of water. After 90 minutes it contains 17.7 cm³. A sealed control loses no water. The student claims that all 6.3 cm³ must have evaporated from the leaves.
.1
Calculate the shoot's mean uptake rate.
[2 marks].2
Evaluate the claim about evaporation.
[2 marks]During exercise a patient's heart rate is 120 beats/min and each side pumps 110 cm³ per beat. Cardiac output is the volume pumped by one side per minute.
.1
Calculate cardiac output in dm³/min.
[2 marks].2
Explain how increased cardiac output supports exercise.
[3 marks]