Transport

Question 1

Define passive transport

Answer 1

Movement of substances across a cell membrane (high to low) without using energy (ATP).
Includes: diffusion, osmosis, and facilitated diffusion.

Question 2

Define diffusion

Answer 2

Movement of particles from an area of high concentration to low concentration until evenly spread out.

Question 3

Define osmosis

Answer 3

The diffusion of water across a semi-permeable membrane from an area of high water concentration to low water concentration.

Question 4

Define facilitated diffusion

Answer 4

Passive movement of particles through a transport protein in the membrane.
Used for molecules that are too large or charged to pass directly through.

Question 5

Define active transport

Answer 5

Movement of substances against the concentration gradient (low to high), which requires energy (ATP) and uses a protein pump.

Question 6

Purpose of active pumps in the membrane

Answer 6

Protein pumps move substances against their gradient using ATP.
They help maintain the right balance of ions and molecules inside the cell.

Question 7

Explain endocytosis/Phagocytosis and exocytosis

Answer 7

Endocytosis- Cell engulfs large particles or fluids by wrapping the membrane around them and forming a vesicle inside the cell.

Exocytosis- Cell releases large molecules by fusing a vesicle with the membrane and pushing contents out the cell.

Question 8

Hyper tonic definiton

Answer 8

A solution with more solutes than the cell → water moves out, cell shrinks.

Question 9

Hypotonic definiton

Answer 9

A solution with fewer solutes than the cell → water moves in, cell swells.

Question 10

Isotonic definiton

Answer 10

Solution has equal solute concentration as the cell → no net water movement.

Question 11

Carrier proteins definition

Answer 11

Proteins in the membrane that carry substances across, often used in facilitated diffusion and active transport.

Question 12

Osmoregulation definition

Answer 12

The control of water and solute balance inside a cell or organism to maintain homeostasis.

Question 13

Why is water balance important in cells?

Answer 13

Water balance keeps cells functioning properly. In plant cells, enough water makes them turgid (firm), helping the plant stay upright. If too much water is lost, they become flaccid (soft) and the plant wilts. In animal cells, too much water causes lysis (bursting), while too little water makes them shrink (crenate). Maintaining water balance ensures normal shape and function of cells.

Question 14

What is the structure and function of the cell membrane

Answer 14

Structure: The cell membrane is a phospholipid bilayer with embedded proteins.
Functions:

Semi-permeable: selectively allows substances in and out.

Maintains homeostasis: controls the internal environment of the cell.

Transport proteins: channel proteins allow substances to pass through, and carrier proteins help move specific molecules across the membrane

Question 15

What factors affect the rate of diffusion across a membrane

Answer 15

Concentration gradient: Steeper gradients = faster diffusion.

Temperature: Higher temperatures increase kinetic energy, speeding up diffusion.

Surface area to volume ratio: Larger SA:V allows more efficient transport.

Membrane permeability: Easier passage = faster diffusion.

Size and polarity of molecules: Small, non-polar molecules (O₂, CO₂) pass easily; large or charged molecules need facilitated diffusion or active transport.

Question 16

what type of energy is used in protein carriers

Answer 16

adp= atp with a missing phosphate

Question 17

transcription

Answer 17

Transcription is when a gene on the DNA is copied to make mRNA.

The DNA strand unwinds.

Free RNA nucleotides match to the template strand (A–U, C–G).

This forms a strand of mRNA, which leaves the nucleus and carries the instructions to the ribosome.

Question 18

translation

Answer 18

Translation is when the mRNA code is used to build a protein.

The mRNA attaches to a ribosome.

tRNA brings amino acids to the ribosome.

Each tRNA matches an mRNA codon.

The amino acids join together in the correct order to make a polypeptide/protein.

Question 19

why things are hypotonic and hypertonic

Answer 19

hypotonic: more water inside the cell because the gradient for the soloute(salt) is low outside the cell so will follow the gradient

hypertonic: less water inside the cell because there ii less water outside the cell and will follow the high to low gradient

Question 20

why sex linked genes cant be independtly assorted

Answer 20

Since the X and Y don’t form a normal homologous pair, those genes can’t separate and mix the same way autosomal genes do.