Biology Questions
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This system of classification is described as hierarchical. Explain what is meant by a hierarchical classification
Organisms can be classified using a hierarchy of phylogenetic groups.Explain what is meant by a phylogenetic group.
This system of classification consists of a hierarchy. Explain what is meant by a hierarchy
Cytochrome c is a protein found in all eukaryotes. In humans it consists of 102 amino acids. Biologists have compared the amino acid sequence in some other species with that in humans. The table shows amino acids 9 to 13 in the amino acid sequences of cytochrome c from four species.Suggest one advantage of using cytochrome c to determine relationships between species.
Cytochrome c is a protein involved in respiration. Scientists determined the amino acid sequence of human cytochrome c. Cytochrome c is more useful than haemoglobin for studying how closely related different organisms are. Suggest one reason why
There are many different species of field mouse in Europe. Using a phylogenetic classification, all of these species have names that start with Apodemus. Describe how breeding experiments could determine whether the two populations are from the same species.
Scientists used DNA hybridisation to confirm the relationship between D. mauritania, D. sechellia and D. yakuba. They made samples of hybrid DNA using a gene that was found in all three species. Explain why it was important that they made samples of hybrid DNA from the same gene.
Despite differences in form, leopards, tigers and lions are classified as different species of the same genus. Cheetahs, although similar in form to leopards, are classified in a different genus. Describe three ways by which different species may be distinguished.
More recently, biologists have used DNA hybridisation to confirm the relationships between different species of crane. They made samples of hybrid DNA from the same and from different species. They measured the percentage of hybridisation of each sample. The biologists measured the temperatures at which the samples of hybrid DNA separated into single strands. Explain why these temperatures could be used to find the percentage of DNA hybridisation.
In most domesticated animals, the morula consists of what?
Polyspermy occurs more frequently in what species?
How does cleavage occur in mammals where a small amount of yolk is present and equally distributed (Isolecithal egg)?
The speed of division is inversely proportional to what?
In most of the species, how long does the sperm remain viable within the female genital tract?
When does the first meiotic division resume in female mammals?
In fowl, how long does the sperm remain viable within the female genital tract?
In horses and dogs, how long does the sperm remain viable within the female genital tract?
The secondary oocyte must be what before second meiotic division is completed?
In horse and dog, what is released (ovulated) for both meiotic divisions to occur after being stimulated by the penetration of sperm?
What structure secretes progesterone to facilitate the implantation and maintenance of the conceptus?