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IGCSE Biology Notes 2024/2025/2026/2027/2028 Exams

 

IGCSE Biology Notes for 2024/2025/2026/2027/2028 Exams

Characteristics and Classification of living organisms Notes

Organisms and their environment IGCSE Biology Notes

  •  2.1-CELL-STRUCTURE
  •  2.2-SIZE-OF-SPECIMENS

Key Points from IGCSE Past Papers Biology

Key Points from IGCSE Past Papers Biology

Questions on Leaf

  • 1.Why is Leaf considered as an organ  [ may-2023-paper-42]  Ans: Leaf is made of   tissues . these tissues  work together  for a specific (named) function. hence leaf is an organ
  • 2. WHAT IS THE MAIN FUNCTION OF STOMATA? [ MAY-2023-PAPER-42] 

Ans: Main Function of stomata is gas-exchange or regulation of transpiration

Questions on DNA and Genes

  • 1.  STATE THE NAME GIVEN TO A LENGTH OF DNA THAT CODES FOR A PROTEIN. [ MAY-2023-PAPER-42] 

Ans: Gene

Questions on Antibiotic Resistance

  • 1. EXPLAIN HOW BACTERIA BECOME RESISTANT TO ANTIBIOTICS. [ MAY-2023-PAPER-42]  

ANS: Bacteria become resistant to antibiotics through a process driven by random mutations, genetic variation, natural selection, and the passing on of resistant genes. Random mutations create genetic diversity, some bacteria develop resistance, survive antibiotic treatment, and reproduce, passing on resistant genes to offspring or other bacteria. This leads to an increase in the frequency of resistant alleles in the population, as bacteria become better adapted to their environment through natural selection.

Questions on Bacteria 

  • 2.BACTERIA ARE PROKARYOTES. STATE TWO FEATURES OF ALL PROKARYOTES. [ MAY-2023-PAPER-42] ANS: FEATURES OF BACTERIA ARE:CELL WALL ; CIRCULAR DNA ; DNA IS, FREE IN CYTOPLASM ,CELL MEMBRANE ; CYTOPLASM ; RIBOSOMES ; UNICELLULAR / SINGLE-CELLED (ORGANISMS) ; ASEXUAL REPRODUCTION ;
  • 3.SOME BACTERIA HAVE A FLAGELLUM. STATE THE FUNCTION OF A FLAGELLUM. [ MAY-2023-PAPER-42] ANS: MOVEMENT  OR SWIMMING 

 

 

Questions on Seed Germination

  • 1. Seeds require oxygen and water to germinate. (i) State one other environmental condition that affects germination. [ MAY-2023-PAPER-42]  

 

Ans: One other environmental condition that affects germination is soil pH.

  • .SUGGEST WHY OXYGEN AND WATER ARE REQUIRED FOR GERMINATION  [ MAY-2023-PAPER-42]      

 

Ans:

  1. Oxygen (Aerobic Respiration): Oxygen is required for aerobic respiration, the process by which seeds break down stored energy reserves to fuel initial growth during germination. Aerobic respiration is more efficient than anaerobic respiration, providing the necessary energy for metabolic activities and cell division.

  2. Water (Used for Turgor): Water is vital for maintaining turgor pressure in plant cells. During germination, water uptake causes the seed to swell, initiating metabolic processes and activating enzymes necessary for growth. Turgor pressure provides structural support and allows seedlings to emerge from the soil. Additionally, water serves as a medium for transporting nutrients and essential molecules within the seed and seedling, facilitating cellular processes essential for germination and early growth.