Practice questions all topics

State the function of the mitochondria.

The site of respiration in plant and animal cells

State the function of the chloroplasts.

The site of photosynthesis in a plant cell

State the function of the cell membrane.

Controls what comes in and goes out of all cells

State the function of the cytoplasm.

Site of chemical reactions in the cell

State the function of the vacuole.

A large, cell sap-filled space in plant cells

State the function of the nucleus.

Contains DNA and controls the cell activities

State the function of the ribosomes.

Bead-shaped organelles which are the site of protein synthesis

Describe the composition and functions of the cell wall.

Are fully permeable, give the cell support and shape, and are made of cellulose (plants) and different materials in bacteria and fungi

What is the name of the small circular pieces of DNA in bacterial cells?

plasmids

Where is the genetic material of a bacterial cell found?

Free in the cytoplasm

State three differences between animal and plant cells.

Plant cells have chloroplasts, vacuole and cellulose cell wall. Animal cells do not

Convert 5 mm to µm.

5000 µm

Name the two substances that the cell membrane consists of

phospholipids and proteins

What does a selectively permeable membrane mean?

Membrane that only allows some types of substances to pass through

Define passive transport

Down the concentration gradient and does not require energy.

Name two types of passive transport in cells

Diffusion and osmosis

Define diffusion

The movement of molecules down a concentration gradient from a higher to a lower concentration

Define osmosis

The movement of water molecules from a high water concentration to a low water concentration through a selectively permeable membrane

Name a substance that diffuses into our cells for use.

Oxygen, glucose

Name a substance that diffuses out of our cells to be removed.

Carbon dioxide, urea

What does 'net movement' mean?

Overall movement: the direction that most of the particles are moving in

State three factors that affect the rate of diffusion.

Concentration gradient, temperature, surface area

How does concentration difference affect the rate of diffusion?

Higher concentration difference/Steeper concentration gradient --> faster diffusion

If a cell is in a solution of a lower water concentration, water will ___ (enter/leave) the cell.

Leave

If a cell is in a solution of a higher water concentration, water will ___ (enter/leave) the cell.

Enter

What will happen to an animal cell in a lower water concentration?

Water leaves cell --> shrinks

What will happen to an animal cell in a higher water concentration?

Water enters cell --> burst

Why do animal cells burst in lower water concentration solutions?

No cell wall

What will happen to a plant cell in a lower water concentration?

Water leaves cell --> plasmolysed

What will happen to a plant cell in a higher water concentration?

Water enters cell --> turgid

What does 'plasmolysed' mean?

The cell membrane pulls away from cell wall

How do we calculate % change in mass?

(final mass - initial mass)/initial mass x 100

Define active transport

The movement of molecules and ions against the concentration gradient using energy and membrane proteins

Explain the importance of active transport in plants.

Root hair cells carry out active transport to absorb mineral ions effectively in dilute soil

State one adaptation cells may have if they need to carry out active transport.

Lots of mitochondria to release energy via aerobic respiration

How does active transport differ from diffusion and osmosis?

Active transport uses energy, diffusion and osmosis do not

State two differences between diffusion and osmosis.

D: Any particles, does not need a membrane; O: Water specific, needs partially permeable membrane

What is the function of DNA

The genetic information for making proteins

Describe the structure of a DNA molecule

A double-stranded helix

Name the three parts of a DNA molecule.

A phosphate group, a sugar molecule and a nucleotide base

Name the complementary base pairs

A-T, C-G

The base sequence determines

The amino acid sequence in a protein

Describe mRNA

A complementary copy of the code from the DNA, in the nucleus, carried to a ribosome

Which organelle synthesises proteins?

ribosome

What is a gene?

a section of DNA which codes for a protein

What are chromosomes?

Structures in the nucleus that carry genes, made of DNA

Name the structure within which DNA is contained.

Chromosomes

What does the sequence of amino acids control?

Controls the shape and function of proteins

What are the 5 types of proteins?

Structural, hormones, antibodies, receptors, enzymes

Describe the role of structural proteins

Hold tissues together e.g. collagen

Define hormones

Chemical messengers which carry a message from a gland to a receptor via the blood

What are antibodies?

Proteins, made by white blood cells, which destroy pathogens by binding to them

Define receptors

Bind to a hormone and tell the target cell what to do.

Define enzymes

Biological catalysts

Describe a biological catalyst

Speeds up chemical reactions in cells and remain unchanged in the process

Define active site

Where the substrate fits into the enzyme and is a complementary shape to it

Define substrate

The reactant(s) in a reaction, and is specific to an enzyme

Define product

The molecule(s) made by an enzyme-controlled reaction

Define optimum conditions

The temperature and pH which the enzymes are most active

Define denatured

When the active site changes shape, the substrate no longer fits, and this affects the rate of the reaction

An example of a degradation reaction is

Starch then amylase then maltose

An example of a synthesis reaction is

G-1-P phosphorylase starch

How does temperature affect enzymes' rate of reaction?

As temperature increases ,the rate of reaction increases until after the optimum is reached when rate of reaction rapidly decreases to zero

Why do enzymes stop working past their optimum temperature?

Enzyme is denatured (substrate can no longer bind to active site)

Why do enzymes not work well at lower temperatures?

There is not enough kinetic energy for the substrate to collide and bind to active site

How does a change in pH affect enzyme structure?

pH change affects the bonds holding enzyme structure together, causing it to denature

What is genetic engineering?

Transferring genetic information (DNA) from one species' cell into another

List the 6 steps in genetic engineering, in order:

1. Identify the gene required on the source chromosome 2. Extract (cut out) the required gene 3. Extract the plasmid from the bacterial cell 4. Insert the required gene into a bacterial plasmid 5. Insert the plasmid into the host cell (bacteria) 6. to produce a GM organism

What 2 things are enzymes are needed for in genetic engineering

Cut the DNA to extract the gene, cut the plasmid open and seal the gene into the plasmid

State the word equation for aerobic respiration.

Glucose + Oxygen --> Carbon dioxide + Water

Respiration is defined as

A series of enzyme-controlled reactions which release the chemical energy stored in glucose

What is the energy released from respiration is transferred to?

ATP

State 5 uses for the energy transferred from ATP in the cell

muscle cell contraction, cell division, protein synthesis, transmission of nerve impulses, active transport

In glycolysis, state what one glucose molecule gets broken down into

Two molecules of pyruvate and released enough energy for 2 ATP

State what happens in stage 2 of aerobic respiration

Each pyruvate is broken down to carbon dioxide and water, releasing enough energy to yields a large number of ATP molecules.

How many ATP are produced by fermentation

2 ATP.

What are the products of plant and yeast cell fermentation

The pyruvate molecules are converted to ethanol and carbon dioxide

What is the product of pyruvate in animal cell fermentation

The pyruvate molecules are converted to lactate

Where in the cell does respiration begin

The cytoplasm

Where in the cell is fermentation completed

The cytoplasm

Where in the cell is aerobic respiration completed

The mitochondria

What is fermentation?

The breakdown of glucose in the absence of oxygen to release a small amount of energy

State an effect on your body after fermentation.

Muscle fatigue

What is the name of the equipment used to measure the rate of respiration?

Respirometer

Species

A group of similar organisms which can produce fertile offspring

Define 'biodiversity'.

The variety of species living in a habitat

Define 'population'.

All the organisms of one species in a habitat

What are producers?

Organisms which produce their own food e.g. plants

Define: Consumer

Organisms which rely on eating other organisms for food

Define: Carnivore

A meat-eater(someone who eats animals)

Define: Herbivore

A plant-eater

Define: Omnivore

An organism which eats both plants and animals

Define: Predator

An organism which hunts for food

Define: prey

An organism which is hunted

Define: Food chain

The feeding relationships between a producer and a top consumer

Define: Food web

A network if interconnected food chains in a habitat

What are primary consumers? Give an example.

Animals that eat producers - Any herbivores (eg. cows, sheep, rabbits)

What are secondary consumers? Give an example.

Animals that eat primary consumers - Any carnivores (eg. lions, foxes, eagles)

Secondary consumers may be eaten by...?

Tertiary consumers

Define 'community'.

A group of interdependent organisms containing different species