random

Question 1

what does the waxy cuticle prevent in plants

Answer 1

water loss

Question 2

What does the upper epidermis allow in plants?

Answer 2

Transmission of light

Question 3

Describe the events of fertilisation that occur after the acrosome reaction. (3)

Answer 3

 fusion of sperm cell (membrane) with egg cell membrane (1)
 cortical granules release contents (into zona pellucida) (1)
 contents of cortical granules react with the zona pellucida /
zona pellucida { thickens / hardens } (1)
 fusion of { sperm and egg / haploid } nuclei (1)

Question 4

Describe the role of the CFTR protein in ensuring that the mucus produced in the lungs has the right consistency (3)

Answer 4

 chloride ions leave cells (through the CFTR channel protein) (1)
 sodium ions leave the cells (following the chloride ions) (1)
 increasing the solute concentration in the mucus (1)
 water moves out of the cells by osmosis (into the mucus) (1)

Question 5

Describe the light-dependent reactions of photosynthesis (5)

Answer 5

use of light (energy) to excite electrons in chlorophyll (1)
 {photolysis / splitting of water} to
produce oxygen, electrons and hydrogen ions (1)
 electrons used { in the electron transport chain / to replace those lost by chlorophyll } (1)
 generation of ATP / chotophosphorylation (1)
 reduction of NADP (1)

Question 6

In which part of the chloroplast do the light-independent reactions take place?
(1)

Answer 6

Stroma

Question 7

What is the name of the enzyme used by plants to fix carbon dioxide? (1)

Answer 7

RUBISCO (ribulose bisphosphate carboxylase/oxygenase)

Question 8

Once the blood vessel/endothelium is damaged, what is the first stage of atherosclerosis/ blood clotting?

Answer 8

Atherosclerosis: inflammatory response where WBCs move into artery(and increased risk of blood clot)
Blood clotting: Platelets attach to exposed collagen fibres

Question 9

What protein is released from platelets to convert prothrombin into thrombin?

Answer 9

Thromboplastin

Question 10

What enzymes does DNA replication use?

Answer 10

DNA helicase
DNA polymerase

Question 11

What enzymes does Protein synthesis use?

Answer 11

Transcription: DNA helicase, RNA polymerase
Translation: NA

Question 12

During atherosclerosis, a build up and hardening of what substances cause a plaque

Answer 12

WBCs, Cholesterol, Calcium salts, fibres

Question 13

How do chloride ions move into cells?

Answer 13

Facilitated diffusion through a channel protein
Chloride ions are charged, therefore do not interact with the hydrophilic tails in the phospholipid bilayer

Question 14

How does oxygen move into cells?

Answer 14

Simple diffusion
Small, non polar molecule

Question 15

How does water move into cells?

Answer 15

Osmosis/ facilitated diffusion (aquaporins)
Water is polar so does not interact well with the hydrophobic tails, but can fit through gaps in phospholipids

Question 16

How do hormones move out of cells?

Answer 16

Exocytosis through vesicles
Too large

Question 17

How does glucose (against conc gradient) move into cells?

Answer 17

Active transport (carrier protein with ATP)
Too large

Question 18

What is needed in the mixture for PCR to take place?

Answer 18

Primers
Free nucleotides
DNA polymerase
DNA sample

Question 19

Describe the process of PCR

Answer 19

Mixture created
Denaturation - Separates the two strands of DNA (95c)
Annealing - Primers bind to the DNA strands (50-65c)
Extension - Allows the DNa polymerase to synthesise (72c)
Two new copies of the fragment of DNA have now been formed
Each cycle doubles the amount of DNA

Question 20

What are the bonds between between two dna strands?

Answer 20

The two strands of DNA are held together by hydrogen bonds that form between specific base pairs

Question 21

What bonds link nucleotides?

Answer 21

Nucleotides in DNA and RNA are linked together by phosphodiester bonds
These bonds form between the phosphate group of one nucleotide and the sugar (deoxyribose in DNA, ribose in RNA) of the adjacent nucleotide. This creates a sugar-phosphate backbone, which forms the structural framework of DNA and RNA.

Question 22

Where are peptide bonds found?

Answer 22

Peptide bonds are found in proteins and peptides, connecting amino acids to form polypeptide chains

Question 23

In what direction does dna polymerase move?

Answer 23

DNA polymerase adds nucleotides to the growing DNA strand in the 5’ to 3’ direction.