IGCSE Biology Paper-4: Specimen Questions with Answers 130 - 131 of 279

Glide to success with Doorsteptutor material for Bank-PO : get questions, notes, tests, video lectures and more- for all subjects of Bank-PO.

Passage

Plants produce glucose in leaves and convert some of it to sucrose.

Question 130 (5 of 7 Based on Passage)

Edit

Write in Short

Short Answer▾

Roots can be an example of a sink.

Explain why sometimes roots act as a source rather than a sink.

Explanation

Belowground organs of plants (e. g. roots and rhizomes) are sinks during plant growth since they cannot perform photosynthesis. Some organs are both a source and sink. Leaves are sinks when growing and sources when photosynthesizing. Rhizomes are sinks when growing but become sources in the spring when they provide energy for new growth.

Question 131 (6 of 7 Based on Passage)

Edit

Write in Short

Short Answer▾

Amino acids are also transported through plants.

State the name of the mineral ion that is used to make amino acids.

Explanation

Nitrogen

  • Source: The chief source of nitrogen for green plants is the soil. It is absorbed mainly in the form of nitrate ions . The major sources of nitrate for the plants are sodium nitrate, potassium nitrate, ammonium nitrate and calcium nitrate. Under suitable conditions, ammonium ions may substitute for nitrate ions, being easily absorbed by plants. Ordinary green plants cannot utilize elemental nitrogen which constitutes about of the air. It is also trapped by nitrogen fixing bacteria which live symbiotically in root nodules of the plants.
  • Functions: Nitrogen is an essential constituent of proteins, nucleic acids, vitamins, and many other organic molecules as chlorophyll. Nitrogen is also present in various hormones, coenzymes, and ATP etc. It plays an important role in protein synthesis, respiration, growth and in almost all metabolic reactions.

Developed by: