NCERT Solutions for Class 11 Biology Chapter 3
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Plant Kingdom: Solutions
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Important Terms on Plant Kingdom
- Numerical Taxonomy: Carried out using computers, Based on all observable characteristics, Data processed after assigning number and codes to all the characters. Advantages: Each character gets equal importance and a number of characters can be considered.
- Cytotaxonomy: Based on cytological information. Gives importance to chromosome number, structure and behaviour.
- Chemataxonomy: Based on Chemical constituents of the plants.
Importance of Algae
- Help in carbon dioxide fixation by carrying out photosynthesis and have immense economic importance.
- At least half of the total carbon dioxide fixation on earth carried out by them.
- Increases dissolved oxygen level in their environment.
- Many species like Laminaria, Sargassum, Porphyra etc. are used as food.
- Agar obtained from Gelidiumand Gracilaria which is used in ice-creams and jellies and to grow microbes.
- Algin obtained from brown algae and carrageen from red algae used commercially as hydrocolloids.
- Chlorella and Spirullina are unicellular algae, rich in protein and used even by space travellers.
- Algae are unicellular like Chlamydomonas, colonial like Volvox or filamentous like spirogyra and Ulothrix.
- Occur in water, soil, wood moist stones etc.
Reproduction in Bryophytes
- Vegetative reproduction by fragmentation.
- Asexual reproduction by gemmae formed in gemma cups.
- Sexual reproduction: Main plant body is haploid, produces gametes and so called Gametophyte. By fusion of antherozoids produced in antheridium and egg cell produced in archegonium, results in formation of zygote which develops into sporophytic structure differentiated into foot, seta and capsule.
- Spores produced in a capsule germinate to from free-living gametophyte (Protonema).
- Sporophyte is not free living but attached to photosynthetic gametophyte from which derives nutrition.
Reproduction in Algae
- Vegetative reproduction: by fragmentation
- Asexual Reproduction: Flagellated zoospores in Chlorophyceae, Biflagellated zoospores in Phaeophycease,
- By non-motile spores in Rhodophyceae.
- Sexual Reproduction: Isogamous, anisogamous or oogamous in chlorophyceae and Phaeophyceae.
- By non-motile gametes and oogamous in Rhodophyceae.