Answer: Option A
Explanation:
A tunicate is marine invertebrate animal which is a part of chordates. They have notochords and dorsal nerve chord. The subphylum of the organism is called as Urochordata.
The adult urochordates lack notochord but the larval stage of the urochordates have notochord. This is because it helps in swimming of the organism which is required only at the larval stage.
The adult stage of the tunicates is sessile and they do not swim so they do not require notochord.
Answer:
The process where part of the DNA is saved during replication is known as semi conservative replication.
Explanation:
During cell division, a cell must first replicate its DNA (Deoxyribonucleic acid). When a cell divides into daughter cells , the DNA of the parent cell must be copied because DNA contains the genetic material of an organism. DNA replication is the process in which DNA is copied during the cell division cycle. During replication, the complementary strands of the original double helix DNA are separated and one of the two strands in the original molecule is saved in the new DNA molecule. Thus the new DNA molecule is made of an original strand and a newly synthesized strand. So the DNA replication is known as semi conservative replication. Each strand of the original DNA molecule is referred as the template strand because it provides information for the production of newly synthesized strand. It takes place inside the nucleus
of a cell during the s stage of the cell cycle. During replication, helicase enzyme breaks the hydrogen bonds between the complementary bases (Adenine with Thymine, Cytosine with Guanine) and unwinds the double helix of DNA. The two separated strands create a Y-shaped replication fork and act as templates for the synthesis of new strands of DNA. Enzymes known as DNA polymerases create the new strands.
Answer:
The other members o the groups help them to survive by taking care of the pups.If it want for them maybe they would die.So the social or connection they have with them will help them to connect with them when they grow
I would say fossilization
Answer:
Here are the answers:
a. 4 Cell determination as an issue in the *rest is missing*
b. 4 They assumed that different ways of separating an embryo into two parts would be equivalent as far as the fate of the two parts was concerned.
c. 4 I and III only
Explanation:
The passage demonstrates the importance of two factors in the development of an embryo: cleavage planes of division of embryonic cells and cell differentiation.
Cleavage Planes:
Cleavage basically refers to the division of the zygote into a large number of cells called blastomeres. Cleavage planes are geometrical lines or orientations along which cleavage takes place. Since, all embryonic cells are the precursors of some type of body cells, the cleavage planes determine if the cells are adequate for growth and development.
Cell Differentiation:
Cell differentiation is the transition of an undifferentiated cell into a specialized one. For example, stem cells are undifferentiated cells that develop into progenitor cells that mature into a specific cell lineage. For an embryo to regenerate, the presence of adequate embryonic stem cells is crucial. Embryonic stem cells are present in abundance before the gastrulation phase of embryonic development, after which they rapidly start differentiating.
