Organism Level Systems | OCR GCSE Combined Science Biology, Higher tier (J250)

Organism Level Systems

108 questions
8 subtopics
Paper 7 (Biology)
Paper 7 (Biology)

Organism Level Systems is examined in Paper 7 (Biology).

It covers the nervous system and coordinated responses, the reflex arc, hormonal coordination, thyroxine and adrenaline, hormones in reproduction and the menstrual cycle, contraception and treating infertility, homeostasis and control systems in the body, insulin and glucagon in blood sugar control and type 1 and type 2 diabetes.

Sample questions from Organism Level Systems

Answer each one closed book first, then open the answer.

The nervous system and coordinated responses

What is an effector?

Show the answer
A muscle or a gland that carries out the response when an impulse arrives from a motor neurone.
The reflex arc

Explain why a reflex arc produces a faster response than a voluntary action.

Show the answer
The impulse passes through only three neurones and two synapses and does not travel to the conscious part of the brain for a decision to be made.
Hormonal coordination, thyroxine and adrenaline

Where are the adrenal glands found?

Show the answer
One sits just above each kidney.
Hormones in reproduction and the menstrual cycle

What is the role of progesterone in the menstrual cycle?

Show the answer
It maintains the thick lining of the uterus so it is ready for a fertilised egg to implant.
Contraception and treating infertility

What is sterilisation, and why does it suit only some people?

Show the answer
The sperm ducts or the oviducts are cut or tied so gametes can never meet; it is meant to be permanent and is very difficult to reverse.
Homeostasis and control systems in the body

Why must body temperature be held close to 37 °C?

Show the answer
Enzymes work fastest near this temperature and are denatured above it, so metabolic reactions would otherwise run at the wrong rate or stop altogether.
Insulin and glucagon in blood sugar control

What sort of molecule is glycogen and where is it stored?

Show the answer
A large carbohydrate made of many glucose molecules joined together, stored in the liver and in the muscles.
Type 1 and type 2 diabetes

How is type 1 diabetes treated?

Show the answer
With injections of insulin, matched to the person's meals and exercise.

The 8 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
The nervous system and coordinated responses	The central nervous system, what sensory, motor and relay neurones, receptors and effectors do, how sensory and motor neurones differ in shape, synapses and neurotransmitters, what a coordinated response is and why many receptors and connections help, the stages from stimulus to response, catching a falling glass, and why nervous responses are faster than hormonal ones.	16
The reflex arc	What a reflex action is and why it protects the body, the parts of a reflex arc in order, why a reflex is faster than a voluntary action, the relay neurone in the spinal cord, how synapses slow an impulse, the hot pan and blinking reflexes, why a person is aware of a reflex, and why the same stimulus always gives the same response.	10
Hormonal coordination, thyroxine and adrenaline	What hormones and endocrine glands are and how hormones affect only their target organs, the main endocrine glands and sex hormones, how hormonal and nervous responses compare, thyroxine and how thyroid stimulating hormone and negative feedback control it, and how adrenaline prepares the body for action.	16
Hormones in reproduction and the menstrual cycle	Testosterone and oestrogen and what each does at puberty, the roles of FSH, LH, oestrogen and progesterone across the 28-day cycle, what triggers ovulation, the corpus luteum, and how a new cycle begins.	16
Contraception and treating infertility	How the combined pill, implants, injections, patches, condoms, sterilisation and natural methods prevent pregnancy, their effectiveness, advantages and drawbacks, how FSH and LH given as fertility drugs help a woman conceive, the stages, drawbacks, multiple births and ethical objections of in vitro fertilisation, and injecting a single sperm into an egg.	16
Homeostasis and control systems in the body	What homeostasis is, the conditions held constant inside the body, why body temperature stays close to 37 °C, the three parts of a control system, how the body corrects a change in temperature, and why the water content of the blood is controlled.	8
Insulin and glucagon in blood sugar control	The pancreas monitoring blood glucose, how insulin makes cells take up glucose and the liver and muscles store it as glycogen, why blood glucose must be controlled, negative feedback, how glucagon releases glucose from glycogen, insulin and glucagon as antagonistic hormones, what happens after a meal, between meals and during a long run, and the part the liver plays.	16
Type 1 and type 2 diabetes	What type 1 and type 2 diabetes are, when each usually appears, insulin injections and why insulin cannot be swallowed, diet and exercise for type 2, risk factors, symptoms, and glucose in the urine.	10

Organism Level Systems is 108 of the 861 questions in the guide.Get the guide, £7

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.