Grade 10, term 3

Question 1

Define hormones

Answer 1

Hormones are chemicals produced by the body to prompt a response by specific cells. Each hormones targets and activates particular cells and causes a particular response.

Question 2

Define glands

Answer 2

Glands are organs that secretes chemicals or proteins within the body or externally.

Question 3

Define receptors

Answer 3

Receptors are Structures that detect and receive stimuli.

Question 4

Five 2 examples of glands, identify what hormone it produces and the target cell that it affects.

Answer 4

Adrenal gland - secretes adrenaline to target the kidney, liver and blood vessels in order to constrict blood vessels within the kidney and liver. This stimulates the liver to produce higher amounts of glucose to prepare for ‘flight or fight’.

Posterior pituitary gland - produces antidiuretic hormone to target the kidney and stimulates reabsorption of water.

Question 5

Outline 3 key differences between water-soluble and fat-soluble

Answer 5

Hydrophilic hormones are polar hormones derived from amino acids and bind to extracellular receptors to trigger a cascade of events inside the cell, resulting in a cellular response while cannot pass through the cell membrane without assistance. On the contrary, hydrophobic hormones are non-polar molecules derived from cholesterol and need an accompanying molecule to pass through blood but can detach and pass through the cell membrane alone to bind to intercellular receptors to cause gene expression.

Question 6

Explain why signalling molecules only have an effect on their target cells.

Answer 6

Signalling molecules only cause an effect on their target cells because only cells in the body that express particular receptors for a hormone will response to it.

Without a receptor to bind to, hormones will drift pass cells without any affect.

Question 7

Define upregulation

Answer 7

When a cell is promoted to produce more of particular cellular component, such as enzymes and receptors (usually due to a hormone detected)

Question 8

Define downregulation

Answer 8

When a cell is promoted to produce less of a particular cellular component, such as enzymes or receptors (Usually due to a hormone detected).

Question 9

Define negative feedback and give an example

Answer 9

Negative feedback is a process where responses counteract disturbances to keep concentrations of substances within narrow limits for optimal cellular function.

EG - thermoregulation or blood sugar regulation

Question 10

Define positive feedback and give an example

Answer 10

Positive feedback is a process where is a psychological response is amplified to achieve a particular result.

EG - During labor, a hormone called oxytocin is released that intensifies and speeds up contractions.

Question 11

Define neuron

Answer 11

A neuron is specialised cell that carry electrical impulses throughout the body.

Question 12

Identify and briefly explain the function of the major neuron parts.

Answer 12

Cell body -
Nucleus -
Axon - long threadlike structure that conducts electrical impulses
Dendrites - receive sensory stimulation in order for the cell to become active
Nissl substance - structures that synthesis proteins that are essential for transmission of nerve impulses.
Schwann cell - myelinates the axon of Neurons within the PNS.
Node of Ranvier - Nodes of Ranvier are gaps in the myelin sheath coating on the neural axon. The myelin allows the electrical impulse to move quickly down the axon. The nodes of Ranvier allow for ions to diffuse in and out of the neuron, propagating the electrical signal down the axon.

Question 13

Is positive or negative feedback more stable and why?

Answer 13

Negative feedback is more stable as it controls more homeostatic mechanisms.

Mechanisms - receptor, control centre, effector

Question 14

Name the five main receptors and give an example of each (both interceptor and extra-receptor example)

Answer 14

1. Chemoreceptor: IR - oxygen and ion levels in blood, ER - smells and tastes in nose and mouth
2. Mechanoreceptors: IR- pressure, vibrations and balance, OR - pressure, touch, sound or vibrations
3. Photoreceptors: IR - light received by eye, ER - none
4. Thermo-receptor: IR - internal temperature in hypothalamus, ER - air temperature on skin
5. Nociceptor: IR - intense pressure or tension, ER - painful heat/cold or pressure on skin

Question 15

Describe what constitutes the body’s internal environment

Answer 15

The body’s internal environment constitutes from interstitial fluid which is extracellular tissue fluid in spaces surrounding cells and plasma.

Question 16

Define and give an example of exocrine glands and endocrine glands

Answer 16

Exocrine glands secrete substances onto an external surface or body tract (saliva) whereas endocrine glands secrete chemicals or proteins within the body into the bloodstream (insulin and adrenaline)

Question 17

How are glands different to muscles as effectors

Answer 17

Glands can be stimulated through neural and chemical stimulation

Question 18

Define the job of a motor neuron

Answer 18

Motor Neurons carry electronic impulses from the CNS to an effector.

Question 19

Give an example of a hydrophobic hormone

Answer 19

Steroid and thyroid

Question 20

Give an example of a hydrophilic hormone

Answer 20

Peptide and some anime hormones

Question 21

What is the difference between anabolic and catholic reactions? Which one is exergonic and endergonic?
Give examples

Answer 21

Catabolic - breaks down (releases) energy - exergonic reaction
EG. - starch breaks down to sugar

Anabolic - absorbs energy - endergonic
EG. - amino acids are joined

Question 22

What is resting potential

Answer 22

The state of a neural cell membrane at rest, when the outside of the cell is more positive than the inside.

Question 23

Define action potential

Answer 23

The state of a neural cell membrane in active transmission, when inside the cell is more positive than the outside.

Question 24

What dies it mean when the axon of a cell is cell is polarised?

Answer 24

There is potential difference between the inside and outside of the cell - one is more positive than the other.

Question 25

What is a sodium - Potassium pump

Answer 25

A membrane protein that uses energy to transport sodium ions out of, and potassium ions into the cells against their concentration gradients.

Question 26

Define depolarisation

Answer 26

A change in a cells membrane potential so that the inside of the membrane is less negative than the outside

Question 27

Define exocytosis

Answer 27

When the vesicles fuse to the pre-synaptic neuron and release their neurotransmitters into the synapse.

Question 28

Define vasoconstriction

Answer 28

Vasoconstriction is the constricting (narrowing) of blood vessels.

Question 29

Define vasodilation

Answer 29

Vasodilation is the process of dilating (widening) blood vessels.

Question 30

Define metabolism

Answer 30

The sum of all chemicals reactions within an organism to maintain life.

Question 31

What is passive movement?

Answer 31

Movement that does not require energy. Molecules can move across the cell membrane passively as it relies on diffusion.

Question 32

Define diffusion, where does it take place?

Answer 32

Diffusion is the net movement of particles from a region of high concentration to a region of low concentration.

Occurs in lipids and gases (fluids) because the particles in these substances are constantly moving. Take solace wherever concentration gradient exists.

Question 33

Define equilibrium

Answer 33

Particles will continue to move randomly, but at equilibrium they move at equal rates in all directions.

Question 34

How does temperature affect diffusion?

Answer 34

An increased temperature of a substance will increase the kinetic energy of the particles. The particles move faster therefore the rate of diffusion increases.

Question 35

Define facilitated diffusion.

Answer 35

Charged particles such as sodium and potassium ions and relatively large particles such as amino acids and glucose cannot readily pass through the differentials phospholipid bilayer. Facilitated diffusion is the process in which channel and carrier proteins assist such particles to diffuse across the membrane.

Question 36

What factors affect the rate of diffusion? (Two)

Answer 36

Concentration gradient (steeper = faster)
Temperature of substance

Question 37

What factors affect the direction of movement?

Answer 37

1. Chemical - chemical properties of a substance indicate how it will behave in the extra cellular environment and its transport.
2. Physical factors - physical shape of the molecule determines which protein is used during facilitated diffusion.
3. Concentration gradient - steeper = faster.

Question 38

What is Endocytosis?

Answer 38

Due to their size and charge, polar molecules cannot pass through the hydrophobic cell membrane or via transport proteins.
During endocytosis, the cell changes shape by sending out projections that surround the material. Membranes forms a vehicle which stores and transports the substance within the cytoplasm.

Question 39

Define phagocytosis (a process during endocytosis)

Answer 39

During phagocytosis, a cell sends out the projections that surround the solid material and when the projections meet, the plasma membrane fuses. - this results in the formation of a phagocytic vehicle, which stores or transports the substance within the cytoplasm.

Question 40

Define exocytosis

Answer 40

Exocytosis is the process by which large molecules held in vesicles within the cell are transported to the external environment. During exocytosis, the vehicle moves to the plasma membrane, fuses with it & releases its contents to the exterior of the cell.

Question 41

What are proteins?

Answer 41

Made of polymers of amino acids, involved in cross-membrane transport and cell communication.
Two types - integral membrane and peripheral membrane

Question 42

What is Cholesterol?

Answer 42

A Lipid composed of 4 Carbon rings and found alongside phospholipids in the membrane.

Question 43

Define integral proteins

Answer 43

Integrated into the membrane because they have at least one hydrophobic region that anchors them to the membrane’s hydrophobic core.
Some stick partway into membrane while others stretch across from side to side (transmembrane proteins) .

Question 44

What are Peripheral membrane proteins?

Answer 44

Found inside and outside cell surfaces of membranes, attached to either integrated proteins or phospholipids.
Don’t stuck to hydrophobic core as they are more loosely attached.

Question 45

What is a sodium potassium pump?

Answer 45

A membrane protein that uses energy to transport sodium ions out of, and potassium ions into, cells against their concentration gradient.

Question 46

What is osmosis? Is it passive or active movement?

Answer 46

The process of osmosis is defined as the diffusion of water across a differentials permeable membrane from an area of high (low solute) to low concentration (high solute). 
Passive movement (requires no input of energy)

Question 47

Define hypertonic external solution and what happens to the molecules?

Answer 47

If fluids outside a cell are higher solute concentration than the cytoplasm.
- molecules will diffuse out.

Question 48

Define hypotonic and what happens to the molecules?

Answer 48

If fluids outside the cell are lower solute concentration than the cytoplasm.
- water movies look will diffuse through the membrane cells.

Question 49

Define isotonic and what happens to the water molecules?

Answer 49

If fluids inside and outside a cell are of equal solute concentration than the cytoplasm.
- water molecules jostle on both sides of the membrane, moving in both directions equally.