Biology Paper 1 2023

Explain Universal, Degenerate and Non Overlapping

Universal - one triplet codes for one amino acid

Non Overlapping - one base is apart of the same triplet

Degenerate - more than one codon codes for the same amino acid

Describe the mechanism of breathing that causes air to enter the lungs

.-diaphragm contracts and flattens

-external intercostal muscles contracts and ribcage pulls out

-Volume increases

-Pressure decreases

Explain why phospholipids can form a bilayer but triglycerides cannot

-Phospholipid is both hydrophobic and hydrophilic

-Triglycerides is only hydrophobic

-The Phosphate group attracts water

Describe how gas exchange occurs in single-celled organisms and explain why this method cannot be used by large, multicellular organisms.

-Single celled organisms uses only diffusion as a gas exchange method

-larger organisms has a lower sa:v ratio meaning the diffusion would be too slow for efficient gas exchange

Explain how sucrose-transport proteins in leaf cells enable the production of a pressure gradient in the phloem.

-sucrose is co transported into the phloem

-decreased water potential

-water enters via osmosis

Name two enzymes that are involved in replicating the DNA of the human papilloma virus and describe their roles in the replication process

-DNA Helicase - breaks hydrogen bonds to unwind DNA

-DNA Polymerase - Condenses to join two adjacent nucleotides

Describe the role of ATP in the process of translation in protein synthesis

-provides energy

-peptide bonds form between amino acid

Describe and explain two ways that structures in the ileum increase the rate of absorption by this cell.

-microvilli increases the surface area for active transport

-mitochondria provides ATP for active transport

Describe how the process of meiosis results in haploid cells.

-DNA replication

Two Divisions:
-First division of Homologues Chomo

-Second division of daughter cells

-four haploid cells form

Describe how organisms are grouped in a phylogenetic classification system

-Hierarchy of groups with no overlaps

-grouped according to evolutionary history

Describe how the structure of the insect gas exchange system: provides cells with sufficient oxygen and limits water loss.

Tracheole:
-has many branches which increases surface area

-has thin walls for shorter diffusion path

Spiracles:
-hairs around spiracles reduces water loss

-allows diffusion of oxygen