Hey,

Gastrulation and PlacentatioN are the process involved in embryo development.

The gastrulation is a process Involving the development of multilayered embryo from single layered fertilized egg . The process of gastrulation give rise to multiple organs and along with that it also helps in establishment of connection between the mother and the developing embryo commonly called as Placentation .

Hence it is clear that gastrulation leads to development of placenta and therefore Placentation occurs after gastrulation I'm the process of embryo development.

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Hello student,

Microsporogenesis is defined as the formation of microspores from microspore mother cells by meiosis . It occurs inside the pollen sac of the anther.

Megasporogenesis is defined as the process of arrangement of megaspores from the megaspore mother cell. It occurs in the ovule of the ovary.

• Meiosis occurs in both the above cases.
• Structures formed at the end : Microsporogenesis results in haploid microspore forming from the diploid microspore mother cell while megasporogenesis results in haploid megaspore forming from the diploid megaspore mother cell.

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Hello aspirant,

Criss-cross inheritance is inheritance of X linked characters. The characters are transferred from mother to her son and from father to his daughter. Hemophilia C is an example.

Stammering although is a genetic disorder but there is no research yet to classify it under disorder of X linked inheritance. The exact pathophysiology of developmental stammering is unknown. Genetic and environmental factors play a vital role in the onset of  stammering. Various family and twin studies indicate that the genetic influence is not in the form of an exact single gene effect such as autosomal recessive, autosomal dominant, or x-linked in all families. However, some studies have repeatedly implicated heredity as a major factor in the occurrence of stammering .

So, stammering is not criss-cross pattern of inheritance.

Hope this helped.

Hello Aspirant,

• Amphibians of Plant kingdom is called Bryophytes .
• Generally amphibian means they can survive both water and soil .
• Bryophytes can live in both water and soil. For Generally they living on soil for complete their fertilization circle they need water.
• Bryophytes are mostly found on marshy and wet lands.
• Bryophytes can adapt both water nutrients and soil nutrients.
• So, bryophytes are amphibians of plant kingdom.

I think this answer will help you for more information refer your class 12 book

All the best !!!!

commonly the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart There is contraction and relaxation of the muscles in the chambers of the heart which is responsible for the pumping of the blood to the parts of the body. The blood pumped by the right ventricle enters the pulmonary artery, whereas the left ventricle pumps blood into the aorta.The heart is a muscular organ in most animals, which pumps blood through the blood vessels of the circulatory system The pumped blood carries oxygen  and nutrients  to the body, while carrying metabolic waste  such as carbon dioxide  to the lungs This pathway constitutes the pulmonary circulation. The oxygenated blood entering the aorta is carried by a network of arteries, arterioles and capillaries to the tissues from where the de-oxygenated blood is collected by a system of venules, veins and vena cava and emptied into the right atrium. This is the systemic circulation. The type of blood circulation in humans is called as double circulation. These two processes pulmonary and systemic circulation are together called as double circulation. This process is necessary because the blood enters twice in the heart in a single cycle.

hope that the information is helpful to you.

regards

Metastasis is the process by which cancer spreads from the place at which it first arose as a primary tumor to distant locations in the body.

Hello aspirant

Heterocytes are specialized and enlarged cells with thick cell walls . Heterocytes are present in nitrogen fixing cyanobacteria.

Heterocytes lack chlorophyll therefore they are  colourless . They synthesize enzyme nitrogenase . With help of enzyme nitrogenase they perform the function of nitrogen fixation.

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Answer is papaya,date palm e.t.c

Papaya ,date palm e.t.c are dioecious plants.That is both male and female flowers are present in different plants.So autogamy (i.e self-pollination)is prevented and gietonomy (i.e self -pollination on the same plant but different flowers) is prevented.

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