OCR GCSE COMBINED SCIENCE B TWENTY FIRST CENTURY J260 04 FOUNDATION TIER STUDY GUIDE 2026 QUESTIONS WITH MARKSCHEME GRADED A+

OCR GCSE COMBINED SCIENCE B TWENTY
FIRST CENTURY J260 04 FOUNDATION
TIER STUDY GUIDE 2026 QUESTIONS WITH
MARKSCHEME GRADED A+

◉ Prokaryotic Cells. Answer: Do not have a defined nucleus


◉ Nucleus. Answer: controls the cell


◉ Cytoplasm. Answer: Site of chemical reactions


◉ Cell membrane. Answer: Allows substances in and out of the cell


◉ Mitochondria. Answer: Site of respiration


◉ Chloroplasts. Answer: Site of photosynthesis


◉ Cell wall. Answer: Keeps the cell rigid


◉ Vacuole. Answer: Stores water and cell sap


◉ Ribosomes. Answer: Site of protein synthesis

, ◉ Enzymes. Answer: A biological catalyst


◉ High temperatures and the wrong pH cause enzymes to. Answer:
Denature


◉ The part that binds to an enzyme. Answer: Substrate


◉ The substrate binds to the enzymes.... Answer: Active site


◉ The _____________ hypothesis describes how enzymes bind to their
substrates. Answer: Lock and Key


◉ DNA is described as. Answer: A double helix


◉ A polymer. Answer: A chain of repeating monomers


◉ The 4 bases in DNA are. Answer: A, T, C, G


◉ The reactants for photosynthesis are. Answer: water and carbon
dioxide


◉ The products of photosynthesis are. Answer: glucose and oxygen