Secondary egg envelopes, Biology

Assignment Help:

Secondary Egg Envelopes

These are secreted by oviducts and other accessory parts of genital organs while the egg is passing through them from ovary to the exterior.

a) In ovoviviparous sharks the egg is surrounded by a hard shell secreted by shell glands of the oviduct. The shell is drawn out as twisted horns which serve to entangle the egg among sea weeds.

b) In amphibians, the eggs are surrounded by a layer of jelly which protects the egg from adverse effects of sun rays, abrasion as well as from predators (because of its bad taste). The jelly absorbs water and swells.

 c) In birds, reptiles and monotremes, the secondary envelopes include the white of egg surrounding the yolky ovum, followed by inner and outer shell membranes (which are in close contact with one another) and the outermost calcareous shell which is 'porous. The shell is elastic and compressible when the egg is laid but it hardens on exposure to atmosphere.


Related Discussions:- Secondary egg envelopes

Explain selective breeding methods, Explains how selective breeding methods...

Explains how selective breeding methods could be used to produce a population of cats with the short legs. Selective breeding E1: bases explanation on the assumption t

Which molecules has more direct effect, Which of the following molecules ha...

Which of the following molecules has more direct effect in learning and memory? A) norepinephrine B) epinephrine C) glutamate D) acetylcholine E) glycine Please leave justification

What is in a test cross invovle, In a test cross: A.alleles of two genes is...

In a test cross: A.alleles of two genes is always involved. B.One parent must be homozygous recessive C.the physical manifestation of a trait can be deterimined. D.both A and C are

Explain about the light sense, Explain about the Light sense You  must ...

Explain about the Light sense You  must be  aware that when you  enter  into a cinema hall, you  are unable  to  see  and  find  out your  seat  initially for  a few minutes; b

Circulation, Circulation, Respiration and Excretion of Asteroidea Aste...

Circulation, Respiration and Excretion of Asteroidea Asteroids depend upon the circulation of coelomic fluid for the transport of gases and some nutrients. The blood vascular

Assessment of megaloblastic anaemia, Assessment   On observation of a c...

Assessment   On observation of a child with this type of anaemia you will find that in addition to the symptoms  of iron deficiency anaemia there is hyper-pigmentation over knu

Explain the structure and functions of kidney, Explain the Structure and Fu...

Explain the Structure and Functions of Kidney You would have got a clear idea as to where the kidneys are situated. Yes, the kidneys are located in the posterior part of the ab

Rna secondary structure, Most  RNA  molecules  are  single-stranded  but  a...

Most  RNA  molecules  are  single-stranded  but  an  RNA  molecule  should  hold regions  that  can  form  complementary   base  pairing  where  the  RNA  strand loops  back  on  i

Why is it not correct to assert that the dna, Q. Why is it not correct to a...

Q. Why is it not correct to assert that the DNA self- replicates? The DNA is not completely self-sufficient in its duplication process because the replication does not occur wi

If the protein binds to any other proteins, You are studying a gene, and it...

You are studying a gene, and its effects on skin cells. You want to find out A) If the protein made encoded by this gene binds to DNA in a particular place B) if the protein binds

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd