Biology OCR Gateway paper 1

prokaryotic cell

bacteria cell (smaller than animal)

eukaryotic cell

animal cell

Bacteria Cell: Flagella

Like a tail. Allows movement. Bacteria can have 1+

Bacteria Cell: Pilus (s)

Protein structures that extend from the bacterial cell envelope. They attach the cells to surfaces.

Bacteria Cell: Capsule

Protects the cell from the harsh conditions in order for it to survive. Allows them to adhere to surfaces

Plasma membrane

Regulates the transport of materials in and out of the cell

What do bacteria cells not have?

mitochondria, a nucleus or chloroplasts

Describe a nucleotide

makes up RNA or DNA. The base changes

What are proteins made up of?

Amino acids

Describe protein synthesis

Transcription: takes place in the nucleus

base sequence of gene is copied into a complementary template molecule called mRNA. This passes out of the nucleus and into the cytoplasm

Translation: takes place in cytoplasm

The mRNA attaches to a ribosome. Amino acids are brought to the ribosome on carrier molecules (called tRNA)

The ribosome reads the triplets of bases on the mRNA and uses this to join together the correct amino acids in the correct order. Once the protein chain is complete, it folds into its unique shape.

Why is RNA different from DNA?

1. single strand, DNA is a double strand

2. RNA has a base of U instead of T

3. DNA has the sugar deoxyribose whereas RNA has the sugar ribose

4 types of proteins

enzymes, hormones, carrier proteins, structural proteins (e.g keratin)

3 enzymes and what they break down things into

Lipase: Fats → Fatty acids and glycerol. Found in small intestine

Protease: protein → amino acids. Found in stomach, small intestine

Amylase: starch → sugars. Found in mouth, small intestine

What effects enzyme activity?

temperature, pH, substrate concentration, enzyme concentration

anaerobic respiration in yeast and plant cells

Glucose --> ethanol + carbon dioxide

anaerobic respiration

glucose -> lactic acid

is bile an enzyme?

Bile is not an enzyme. It doesn't digest it emulsifies fat droplets.

Rate of photosynthesis

Rate of photosynthesis = 1/time

Inverse square law

When you double the distance from the light source, the LI falls by a factor of 4

1/distance from light source²

factors affecting photosynthesis

light intensity, CO2 concentration, temperature

What does FSH do?

Pituitary gland secretes FSH, which causes an egg in the ovaries to mature- period happens

FSH stimulates the ovaries to release oestrogen

What does oestrogen do?

inhibits FSH and makes the uterus lining repair itself and grow after menstruation (a period) stimulates LH to be released.

What does LH do?

The Pituitary gland releases LH, which causes an egg to be released from the ovaries. This is called ovulation and happens on day 14 of the menstrual cycle.

What does Progesterone do?

Progesterone is released from the empty follicle in the ovaries. It maintains the uterus lining after ovulation. Inhibits LH + FSH. Once levels have decreased the uterus lining sheds again- a period.

What type of reaction is photosynthesis?

Endothermic

What type of reaction is respiration?

Exothermic

What does a potometer measure?

the rate of water uptake by a plant

Diffusion

The net movement of particles from an area of high concentration to an area of low concentration. It's a passive process.

3 ways the rate of diffusion can be increased

- increase the surface area (decreasing diffusion distance)

- increase the temperature

- a greater concentration gradient

Active transport

when particles move from an area of low concentration to an area of high concentration (against the concentration gradient) It requires energy

an example of active transport in plants

ions moving into root hair cells

an example of active transport in animals

glucose molecules moving across the gut wall into the blood

osmosis

the movement of water molecules from an area of high water potential to an area of low water potential across a partially permeable membrane

what is it called when an animal cell looses too much water and shrivels up?

crenulation

what is it called when an animal cell swells up and the cell membrane ruptures due to too much water?

lysis

what is it called when a plant cell becomes swollen due to too much water? (it will not burst due to the cell wall)

turgid

what is it called when a plant cell becomes plasmolysed (it collapses away from the cell wall) due to water loss?

flaccid

name the stages of mitosis

Prophase

Metaphase

Anaphase

Telophase

What happens in Prophase?

chromosomes condense, nuclear membrane disappears

What happens in metaphase?

Chromosomes line up in the middle of the cell

What happens in anaphase?

Chromosomes and their copies are pulled to different ends of the cell.

What happens in telophase?

two new nuclei form

What are the 2 stages of the cell cycle that are not in mitosis?

1. interphase - the cell is growing, replicating its DNA and carrying out its daily functions

6. Cytokinesis- the cell membrane pinches in and eventually divides into two daughter cells

A specialised animal cell

Sperm cell

A specialised plant cell

Root hair cell

Cell differentiation

the process by which a cell becomes specialised

How is the sperm cell specialised?

streamlined shape for swimming, lots of mitochondria, flagellum so the sperm can swim, half as much genetic material as normal adult cell, digestive enzymes to break a hole into the egg when the sperm reaches it

what are the two types of stem cells?

adult stem cells and embryonic stem cells

stem cell

an undifferentiated cell which can give rise to more cells of the same type and can differentiate to form other types of cells

where does cell division in plants occur?

the meristem- at the tip of the root and shoots

How are alveoli adapted for gas exchange?

made up of a layer of very thin cells (short diffusion pathway), very large surface area, alveoli walls are moist, each alveoli is surrounded by blood vessels (they have a good blood supply)

Arteries

carry blood away from the heart

small lumen

thick wall of muscle and elastic fibres

Veins

carry blood to the heart

large lumen

thin wall of muscle and elastic fibres

valves

Capilleries

connect arteries and veins

the wall of the capillary is one cell thick

the lumen is one cell thick

what are the 4 heart chambers called?

right atria, left atria, right ventricle, left ventricle

what are the 4 components of blood?

red blood cells, white blood cells, platelets, plasma

How are red blood cells adapted?

Contain haemoglobin, have no nucleus, have a biconcave shape to maximise SA, they are thin which means a short diffusion distance

what do white blood cells do?

Engulf and destroy unwanted microorganisms that enter the blood

What does plasma contain?

glucose, anti bodies, hormones, proteins, amino acids, carbon dioxide, urea, rbc, wbc, platelets

What are platelets?

Small fragments of cells with no nucleus

what do platelets do?

they float in blood until we get a cut then rush to the wound and act like glue, patching up the hole

What makes up the vascular bundle?

xylem and phloem

how are leaves adapted to absorb light energy?

palisade cells are column shaped and packed with chloroplasts. they are arranged closely together with a lot of light energy absorbed

how do the stomata open?

When cell full of water, guard cells around stomata swell up and open so water can escape. water then leaves the guard cells and they become flaccid and the stomata close

which way does the xylem transport water and minerals in a plant?

Up

which way does the phloem transport sugars in a plant?

up and down

what stiffens the xylem?

lignin

are phloem cells alive or dead?

alive

are xylem cells alive or dead?

dead

transpiration

the loss of water from leaves by evaporation through the stomata

transpiration stream

the constant flow of water from the roots and out the leaves due to transpiration

factors that affect transpiration

light intensity

temperature

wind

humidity

central nervous system (CNS)

brain and spinal cord

Peripheral Nervous System (PNS)

the network of nerves that connects the brain and spinal cord to other parts of the body

3 types of neurones

Sensory, relay and motor

motor neurone

relay neurone

sensory neurone

receptors

groups of specialised cells that detect a change in environment and stimulate electrical impulses in response

effectors

produce a specific response to a detected stimulus (a muscle contracting or a gland releasing a hormone)

a coordinated response sequence

stimulus -> receptor cell -> sensory neurone -> relay neurone -> motor neurone -> effector -> response

synapses

Tiny spaces between neurones. A signal is sent across the synapse by a chemical transmitter

reflex arc

receptor in the skin detects a stimulus. impulses from the receptor pass along a sensory neurone to the relay neurone/CNS. A chemical crosses the synapse between a sensory and relay neurone. Then a chemical crosses the synapse between the relay and motor neurone. The relay neurone sends electrical impulses to an effector. effector produces a response

function of the cornea

refracts light into the eye

what are the two cells found in the retina

rods (light) and cones (colour)

accomodation

the process of changing the shape of the lens to focus on near or distant objects

how is short sightedness treated?

concave lens

what does the medulla control

unconscious activities like heart rate and breathing rate

what does the cerebellum control

posture, balance, coordination of movement and muscular activity, involuntary movements

Explain how thyroxine works

low thyroxine levels in blood = hypothalamus releases TRH

causes the pituitary gland to release TSH

causes the thyroid gland to release more thyroxine

TRH is inhibited

Role of FSH

causes an egg to mature in the ovary, secreted from the pituitary gland, stimulate oestrogen production

Role of Oestrogen

stimulates the uterus lining to repair itself and grow after menstruation, produced in ovaries, inhibits FSH production, stimulates release of LH

What are the two methods of contraception?

hormonal and non-hormonal

Name the hormonal methods of contraception

Combined oral contraceptive pill, progesterone only pill, contraceptive patch (releases oestrogen and progesterone), contraceptive injection of progesterone, plastic iud

How does the combined oral contraceptive pill work?

Oestrogen (at high doses) and progesterone inhibit the production of FSH, and eggs can't mature

How does the progesterone only pill work?

Progesterone inhibits FSH, so eggs can't mature

Name the non hormonal methods of contraception

barrier methods (condom, female condom, diaphragm), sterilisation, IUD/coil, Natural methods like family planning

What is the most reliable (100% pregnancies prevented) method of contraception?

Surgery

What are the 5 stages of IVF?

Woman is given FSH and LH to mature and release eggs

Eggs collected from woman's ovaries

Eggs are fertilised with father's sperm in a lap

Fertilised eggs left to develop into an embryo for 3-5 days

1 or 2 embryos are then inserted into the mother's uterus

5 things that determine if IVF is likely to be successful

Young

Low alcohol intake

Doesn't smoke

'Normal' body weight

Has been pregnant before (not actual NHS criteria)