3. If two species were brought into captivity for hybridization but it was not p

Question

3. If two species were brought into captivity for hybridization but it was not possible to create viable offspring, what are two possible explanations for this failure to interbreed? If it was possible to produce fertile hybrids, and the release of these hybrids to the wild resulted in a stable hybrid zone, how would you explain this? (10pts) 4. Use the phylogenetic tree to answer the questions below. (10pts) Order Family Genus Species Panthera pardus Taxidea taxus % Lutra lutra Canis latrans Canis upus a. The Mustelidae are the sister group for which taxa? b. Which species is the basal taxa to the Carnivora? C. List two species that form a monophyletic group d. List three species that form a paraphyletic group e. To what taxon is Panthera pardis most closely related? f. Coyotes (Canis latcans) and wolves (Canis lupus) both have elongated canine

Explanation / Answer

3. ANS: A. Gametic isolation: In it, eggs on species may be fertilized by the sperm of another species because sperms do not survive in the female reproductive tract of another species.this happens due to the biochemical mechanism that stops sperm from penetrating eggs membrane of another species.

B. Reduced hybrid viability: genes of parents species may combine in that way that stops development of hybrid species.

If it was possible to produce fertile hybrids, and the release of these hybrids to the wild resulted in a stable hybrid zone.Hybrids of the first generation may be fertile but after mating with each other or one of the parent's offspring will be stale. It is known as the hybrid breakdown.

5. ANS: Virus enter the body by direct contact with infected person , like kissing, intercourse , blood transfusion , infected instruments needles etc

Virus replicate within host by forming dna by reverse transcriptase and this dna get incoporated with the host dna and replicate , make viral copies .

On replication of genome and structural protein virus exit the cell by bursting the cell , thus the cell damage during exit of virus particle

Treatment of hiv include non reverse transciptase inhibitor , revertransciptase inhibitor , protease inhibitor . Like zidovudine, indinavir etc.

6. ANS: Fungi are unique organisms. They include large macroscopic mushroom to unicellular yeast.

i. They are multicellular eukaryotic organisms with chitin-made cell wall

ii. Most fungi contain a filamentous body. These filaments are known as hyphae. They can be uninucleate or coenocytic.

iii. Fungi are heterotrophic. Some fungi are saprophytic and others are pathogenic.

iv. Fungi disperse by releasing spores. They show vegetative, asexual and sexual reproductive strategies.

v. They show rapid growth

vi. Many fungi are ecologically important. They play vital roles in nutrient recycling.

vii. Some fungi are used for extraction of antibiotics. Ex: Penicillin from Penicillium.

viii. Some fungi grow as symbionts with algae. These symbionts are known as Lichens. Lichens are the pioneer species in terrestrial succession.

7. ANS: 1. Chitin: This is present in arthopod cuticle which forms the exoskeleton and provides the major support.

2. Calcareous Spicules: They make the support system of proifera

3. Calcium carbonate endoskeleton of echinoderms

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