Biology · Respiration in Plants · NEET
Yes. Plants need O2 for respiration and they give out CO2, exactly like animals. NCERT says the answer is 'not quite so direct' only because plants do it WITHOUT any special organs. So respiration (breathing at the cell level) happens in every living plant cell, all the time, day and night.
NCERT gives three clear reasons. (1) Each plant part handles its own gas needs, so there is very little gas transport from one part to another. (2) Plants respire at a much lower rate than animals, so demand is small (roots, stems, leaves need little gas). (3) The diffusion distance is short - every living cell lies close to the surface, so gases reach it easily by simple diffusion. Because of these, plants can manage without lungs or a circulatory transport for gases.
By diffusion through small openings. Leaves have stomata (pores on the leaf surface). Woody stems and older roots have lenticels (openings in the bark). Inside, loosely packed parenchyma cells create a network of interconnected air spaces, so O2 and CO2 move easily to and from every cell. No pumping, no lungs - just diffusion down a concentration gradient.
This is the most common trap. Plants release O2 only during photosynthesis (in light, in green cells). But respiration still uses O2 and releases CO2 24 hours a day in every living cell. During bright daytime photosynthesis is faster, so net exchange looks like O2 out. At night only respiration happens, so plants take in O2 and give out CO2. Both processes are separate.
No. In woody stems, only the thin layer of living cells inside and beneath the bark respires; these use lenticels for gas exchange. The cells in the deep interior (heartwood) are DEAD and give only mechanical support. So gas exchange is only needed near the living surface - another reason plants get along without respiratory organs.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes. At night there is no photosynthesis, so plants only respire - they take in O2 and give out CO2 through stomata and lenticels.
Stomata are pores on leaves and soft green parts; lenticels are openings in the bark of woody stems and older roots. Both allow gaseous exchange by diffusion.
Because each part handles its own gas needs, respiration rates are low, and diffusion distances are short - every living cell lies near the surface. So diffusion is enough.
For NEET, 'breathing' loosely means gaseous exchange (O2 in, CO2 out), while respiration is the cellular process that breaks down glucose to release energy. Plants do both, without special organs.
All living parts do - leaves via stomata, stems and roots via lenticels and surfaces. Dead interior cells of woody stems do not need gas exchange.
