Biology -Important Points For Competitive Exams

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1-Gas exchange in plants is carried out via simple diffusion.

2-Transpiration is the loss of water from the plant to the atmosphere into the form of vapor.

3-Transpiration occurs through the cuticle of the epidermis (cuticular transpiration) or through the ostioles of the stomata (stomatal transpiration).

4-Stomata (singular, stoma) are small specialized passageways for water and gases present in the epidermis of plants.

5-A stoma is made of a central opening, called the ostiole, or slit, surrounded by two guard cells responsible for closing and opening

6-Water enters and exits stomata via osmosis.

7-Leaves also lose liquid water through a phenomenon known as guttation.

8-Guttation takes place through structures called hydathodes, which are similar to stomata.

9-When air humidity is high, transpiration decreases.

10-In bryophytes, substance transport is carried out by diffusion.

11- Tracheophytes (pteridophytes, gymnosperms and angiosperms) contain specialized conducting vessels: xylem, which carries water and mineral salts, and phloem, which transports organic materials (sugar).

12-Carbon dioxide and oxygen are not transported through xylem or phloem

13-Root pressure is the pressure that forces water from the soil to be absorbed by xylem in the root.

14-Root pressure is caused by the osmotic gradient between the interior of the root and the soil.

15-Plant hormones, also called phytohormones, are substances that control embryonic development and growth in adult plants.

16-The coleoptile is the first (one or more) aerial structure of the sprouting plant that emerges from the seed.

17-Parthenocarpic fruits are those produced without fertilization. Some plants produce parthenocarpic fruits naturally, such as the banana tree

18-Tropisms are movements caused by external stimuli.

19- In botany, the plant tropisms studied are: phototropism (tropism in response to light), geotropism (tropism in response to the gravity of earth) and thigmotropism (tropism in response to mechanical stimuli).

20-Phototropism is the movement of plant structures in response to light.

21-Phototropism may be positive or negative. Positive phototropism is when the plant movement (or growth) is towards the light source and negative phototropism is when the movement (or growth) is opposite, moving away from the light source.

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