GCSE Biology Topic 5

Define 'homeostasis'.

Maintainence of internal environment relatively stable at optimum conditions through negative feedback

Name three key internal conditions that need to be controlled through homeostasis.

Temperature; Water levels; Blood glucose level

Name the cell type that detects stimuli in the internal or external environment.

Receptor

Name the component in the nervous system that processes the stimuli information.

Coordination centre

Name the component in the nervous system that bring about responses to stimuli.

Effectors

State the function of a neurone.

Transmit electrical impulses

Name the type of neurone that carries impulses to the central nervous system.

Sensory neurone

Name the type of neurone that carries impulses away from the central nervous system.

Motor neurone

Name two types of effectors.

Muscle; Glands

Name the two coordination centres that make up the central nervous system.

Brain + Spinal cord

Where is the cell body found in the sensory neurone?

Along/On the neurone fibre

Where is the cell body found in the motor neurone?

At the beginning of the motor neurone

Name one factor that may affect human reaction time.

Energy or sugary drinks/Practise beforehand etc.

What are reflex actions?

Automatic and rapid actions that do not involve the conscious parts of the brain

Name the three types of neurones that are involved in coordinating reflexes.

Sensory, relay, motor neurones

Where is the relay neurone found in a reflex arc?

Spinal cord

Illustrate the reflex pathway in a flowchart, showing all the components involved.

(Stimulus -->) Receptor --> Sensory neurone --> Relay neurone --> Motor neurone --> Effector (--> Response)

What are synapses?

The junction/physical gap between neurones

How is information passed through the synapse?

Neurotransmitters/Chemicals are released, which travel across the synapse to the receptor sites on the next neurone

Name the region in the brain that involves consciousness, intelligence, memory and language.

Cerebral cortex

Name the region in the brain that coordinates muscular activity and balance.

Cerebellum

Name the region in the brain that coordinates automatic, unconscious activities.

Medulla (oblongata)

Name a method scientists used to find out the functions of each part of the brain.

Studying brain damage patients/Electrically stimulating different parts of brain/MRI scans

State the function of the sclera.

White outer layer to protect the eyeball

State the function of the cornea.

Allows light into the eye; Refract/focus light

How is the size of the pupil controlled?

Muscular contraction and relaxation of the iris

State the function of the lens.

Refracts light to focus the image onto the retina

Name the two components that change the shape of the lens.

Suspensory ligaments + Ciliary muscles

Name the component that carries impulses from the retina to the brain.

Optic nerve

Describe the state of the ciliary muscles and the lens as the eye focuses on a distant object.

Ciliary muscles relax, Lens becomes thinner

Name the condition in which people can see close objects clearly but distant objects look blurred.

Myopia/Short sightedness

Name the condition in which people can see distant objects clearly but close objects are blurred.

Hyperopia

Give two possible reasons for myopia.

Lens too curved; Long eyeball

Describe the state of the lens if more refraction is to happen.

More convex/rounded

Name a treatment for myopia or hyperopia.

Contact lenses/Laser eye surgery/Replacement lenses

How does the endocrine system bring about a change in our internal environment?

Glands release hormones into bloodstream, which then travel to the target organ to produce an effect

Name the 'master gland' that secretes a variety of hormones.

Pituitary gland

Name the hormone that affects the amount of urine produced by the kidney.

ADH

State one difference between the effects of hormones compared to the nervous system.

Hormonal effects are slower/last longer

Name the hormone that decreases blood glucose level.

Insulin

Name the hormone that increases blood glucose level.

Glucagon

Name the organ the produces hormones to control blood glucose level.

Pancreas

State an effect of insulin.

Increase glucose uptake by cells/More respiration/Convert glucose to glycogen to store in liver and muscles/Convert glucose to fat for storage

State an effect of glucagon.

Convert glycogen to glucose/Make glucose from amino acids or fat

What is glycogen?

Complex/Storage carbohydrate made up of glucose in liver and muscles

What is type 1 diabetes?

Condition where pancreas does not make enough/any insulin

What is type 2 diabetes?

Condition where body cells stop responding to insulin properly

Name one symptom of diabetes.

Excess urine/Feeling thirsty/Lack energy/Lose weight/Fatigue

Name a risk factor for type 2 diabetes.

Lack of exercise/Sugary diet/Obesity

Name a treatment for type 1 diabetes but not type 2 diabetes.

Insulin injection

Name a method to cure type 1 diabetes.

Pancreas or pancreatic cell transplant

Name one treatment for type 2 diabetes.

Carbohydrate-controlled diet/Lose weight/Regular exercise/Medicine

Which organ produces thyroxine?

Thyroid gland

What is the effect of thyroxine?

Controls metabolic rate

Name the hormone secreted by the pituitary gland that controls the production of thyroxine?

TSH (thyroid stimulating hormone)

State one effect of adrenaline.

Increase heart rate/breathing rate/Increase glycogen conversion to glucose/Pupils dilate/Increase mental awareness/More blood flow to muscles

Name the organ that secretes adrenaline.

Adrenal gland

The level of adrenaline is controlled by a negative feedback system. True or false?

FALSE

Under what sort of situation would adrenaline be released?

In reaction to fear or stress

Name the main female reproductive hormone.

Oestrogen

Name the process where a matured egg is released from the ovaries.

Ovulation

Name the hormone that causes egg maturation in the ovaries.

FSH (follicle stimulating hormone)

Name the hormone that stimulates ovulation.

LH (luteinising hormone)

Name the hormone that stimulates the build-up of the uterus lining.

Oestrogen

Name the hormone that maintains the uterus lining.

Progesterone

Name the main male reproductive hormone.

Testosterone

Which organ produces testosterone?

Testes

State the average length of the menstrual cycle.

28 days

Which two female hormones does the pituitary gland secretes during the menstrual cycle?

FSH and LH

Which two female hormones does the ovaries release during the menstrual cycle?

Oestrogen and progesterone

Which hormone stimulates the release of oestrogen?

FSH

Which hormone inhibits the release of FSH?

Oestrogen

Which hormone stimulates the release of LH?

Oestrogen

Which hormone inhibits the release of both FSH and LH?

Progesterone

Which hormone(s) are used as contraceptive pills?

Oestrogen and progesterone

Name a chemical method of contraception.

Spermicides

Name a barrier method of contraception.

Condom/Diaphragm

Which two hormones are issued as fertility drug in IVF treatments?

FSH and LH

Where does fertilisation occur in IVF treatment?

In a Petri dish

Define 'phototropism'.

The response of a plant to light

Define 'gravitropism/geotropism'.

The response of a plant to gravity

What are auxins?

A plant hormone that controls photo- and geotropism

How do auxins respond to one-sided light on a young shoot?

Auxins move to the unlit side (causing quicker growth, hence the shoot bends towards the light)

How do auxins respond to a young root placed sideways?

Auxins move to the lower side of the root

What is the effect of a high level of auxin on shoot growth?

Auxins promote shoot growth

What is the effect of a high level of auxin on root growth?

Auxins inhibit root growth

Name one use of auxins in agriculture and horticulture.

Weed killers/Rooting powders/Tissue culture

Name one use of ethene in agriculture.

Control fruit ripening

Name one use of gibberellins in agriculture.

Increase fruit size/Stimulate germination/Promote flowering

Name the part in the brain that controls your core body temperature.

Thermoregulatory centre in hypothalmus

Name the action where surface skin capillaries dilate to allow more blood flow to the surface.

Vasodilation

State one response of the body to high body temperature.

Sweating/Vasodilation/Hair lies flat

State one response of the body to low body temperature.

Vasoconstriction/Less sweating/Shivering

Briefly explain how shivering helps increase our body temperatre.

Contractions requires energy from respiration (exothermic)

Name the two main poisonous waste products in our body.

Carbon dioxide + Urea

How does high carbon dioxide level affect the body?

Dissolved CO2 makes acidic solution --> denature enzymes

How is carbon dioxide removed from the cells and out of the body?

Transported to alveoli --> exhaled into environment

How is urea produced?

Breakdown of excess amino acids

Name the organ that removes urea from the body.

Kidney

Name the process which removes the amine group from the amino acids.

Deamination