H02002 - Study guides, Revision notes & Summaries

Pepsin is a protease enzyme with a polypeptide chain containing 327 amino acids. Titin is the largest known protein. It has a polypeptide chain containing at least 92 times more amino acids than pepsin. (i) DNA sequences in genes code for polypeptide molecules such as pepsin and titin. Explain why a process known as transcription is necessary for polypeptide synthesis - ANSWER DNA, copied to mRNA DNA, is too large to leave nucleus Calculate the minimum length of the DNA base sequence r...

Meiosis is a type of nuclear division. Fig. 1.2 shows a photomicrograph of plant cells undergoing meiosis identify the stage of meiosis 1 shown in the cell labelled A - ANSWER prophase (1) Based only on your observations of Fig.1.2, state two reasons for your answer in (b)(i) - ANSWER chromosomes condense chromosomes still not aligned at the equator Another stage of meiosis is metaphase 1. Explain how the organization of homologous chromosomes during metaphase 1 increases genetic varia...

#O C R AS Level Biology A H020/02 Depth in biology May 2023

). Aphids are small insects that feed on the sap that is translocated through the plant in the phloem. These insects insert their fine mouthparts, stylets, into phloem tissue and allow the sap to flow out of the phloem. One method of collecting sap is to allow the aphid to feed as shown in Fig. 1. Fig. 1.1 The aphid is then anaesthetised and the stylet is cut off close to the aphid’s head. The sap can then be collected and analysed. A researcher analysed the sap collected and ...

OCR Biology A (AS) H020_02 Depth in biology question-paper May 2024

OCR Biology A (AS) H020_02 Depth in biology mark-scheme May 2024

Biology A H020/02: Depth in biology AS Level

OCR AS BIOLOGY A PAPER 2 MARK SCHEME 2024 (H020/02: Depth in biology)

2024 AS Level Biology A H020/02 Depth in biology Monday 4 June FINAL UPDATE PASS A+