<span>The mammalian sperm cell consists of a head, a midpiece and a tail. The head contains the nucleus with densely coiled chromatin fibres, surrounded anteriorly by an acrosome, which contains enzymes used for penetrating the female egg.</span>
Sex is a reproduction system involving both male and female to partake in sexual activity intercourse to create an offspring between the two beings creating a living organism
DNA is made of genes. so it is C
Emperor penguins need lungs to breathe. In penguin lungs, air never stops. ... Once the air goes farther into the trachea it splits into two different directions into both lungs. To get the oxygen into the blood cells, it must come "within small distance of the penguin blood cells".
Answer:
Class I: Hepaticopsida ( Liverworts)
Class II: Anthocerotopsida ( Hornworts)
Class III: Bryopsida ( Mosses)
Explanation:
Bryophytes are small plants that grows in moist and shady places.They don't attain great heights because of absence of roots, vascular tissues, mechanical tissues and cuticle. They are terrestrial but require external water to complete their life cycle. Hence they are called as the" amphibians" of the animal kingdom.
Class I: Hepaticopsida or Hepaticae
- Gametophytic plant body is either thalloid or foliose. If foliose the lateral appendages are without midrib.
- Rhizoids without septa
- Each cell in the thallus contain many chloroplasts
- Sex organs are embedded in the dorsal surface
- Capsule lacks columella
- Sporophyte may be simple having only one capsule or differentiated into root, seta and capsule
- It has 4 orders: Calobryales, Jungermanniales, Spherocarpales and Marchantiales
Class 2: Anthocerotae or Anthocerotopsids:
- Gametophytic plant body is simple, thalloid;thallus dorsiventra without air chambers shows no internal differentiation of tissues
- Scales are absent in the thallus
- Each cell of the thallus possess a single large chloroplast with a pyrenoid
- Sporophyte is cylindrical only partly dependent on gametophyte for its nourishment. It is differentiated into bulbous foot and cyclindrical capsule. Seta is meristematic.
- Endotheciumforms the sterile central column in the capsule. It have ony one order Anthocerotales
Class 3: Musci or Bryopsida
- Gametophyte is differentiated into prostrate protonema and an erect gametophores
- Gametophore ids foliose, differentiated into axis and lateral appendages like leaves but without midrib.
- Rhizoids are multicellular with oblique septa
- Elaters are absent in the capsule of sporangium
- The sex organs are produced in seperate branches immersed in a group of leaves.
- It has only three orders: Bryales, Andriales and Sphagnales
Bryophytes are used as a packaging material for fragile goods, glasswares etc.Mosses are good source of animal food in rocky and snow clad areas. Decoction prepared by boiling Sphagnum in water is used for the treatment of eye disease.
