Organisms and Populations — BIOLOGY STD 12 Science — Question

Explain bioreactor with diagram.

Read the following and answer any four questions from (i) to (v) given below:

Mutation explains the relationship between gene and DNA. The effects of large deletions and rearrangement in a segment of DNA results in loss or gain of gene and its function. Insertion or deletion of one or two bases changes the reading frame from the point of insertion or deletion. A classical example of point mutation is a change of single base pair in the gene for beta globin chain that results in change of amino acid residue glutamate to valine and results into a diseased condition called sickle cell anaemia.

1. A mutation is a change produced by an alteration in the genetic mechanism and.

1. May arise spontaneously.
2. Is always induced by the environment.
3. Is never advantageous.
4. Is not inherited.

2. The DNA code for glutamic acid is CTC or CTT. The code for valine is CAA or CAT. In sickle cell haemoglobin, valine is present instead of glutamic acid.

Assuming a single base pair substitution has occurred, what is the mRNA code in the affected mutant?

1. CUU
2. GAA
3. GAG
4. GUA

3. A mutation involving the substitution of one nitrogenous base for another has altered the base sequence of a DNA molecule, coding for four amino acids, as shown below.

Normal A-G-C-A-T-G-G-A-T-C-C-T

Mutant A-G-C-A-T-G-C-A-T-C-C-T

The table shows six codons and the corresponding amino acids into which each is translated.

mRNA codon	Amino acid
AAG	Lysine
CUA	Leucine
GGA	Glycine
GUA	Valine
UAC	Tyrosine
UCG	Serine

The mutation has changed the amino acid.

1. Leucine to valine.
2. Lysine to glycine.
3. Serine to leucine.
4. Tyrosine to lysine.

4. Assertion : Insertion or deletion of three or its multiple bases, insert or delete one or multiple codons and so one or multiple amino acids.

Reason: Reading frame remains unaltered with insertion or deletion of three or its multiple bases.

1. Both assertion and reason are true, and reason is the correct explanation of assertion.
2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
3. Assertion is true, but reason is false.
4. Both assertion and reason are false.

5. Part of the amino acid sequences in normal and sickle cell haemoglobin are shown.

Normal haemoglobin	Sickle cell haemoglobin
Thr-Pro-Glu-Glu	Thr-Pro-Val-Glu

mRNA codons for these amino acids are

Glutamine (Glu) GAA GAG

Praline (Pro) CCU CCC

Threonine (Thr) ACU ACC

Valine (Val) GUA GUG

Which transfer RNA molecule is involved in the formation of this part of the sickle cell haemoglobin?

Describe the process of DNA Fingerprinting in detail.

Read the following and answer any four questions from (i) to (v) given below:

Ginkgo tree has been saved from extinction by selective breeding followed by channeling into trade of nature lovers. This is an ex-situ conservation, where endangered species are protected from all adverse factors. Offspring produced in captive breeding are released in natural habitat for acclimatisation.

1. What is the significance of offsite collections?

1. Restock depleted populations.
2. Protection of endangered species.
3. Reintroduce species in wild.
4. All of these.

2. Which of the following is not an ex-situ conservation?

1. Wetlands
2. Orchards
3. Aquaria
4. Botanical gardens.

3. Select the incorrect statements for ex-situ conservation.

1. It is conservation of species outside their natural habitats.
2. Endangered species are kept under human supervision and provided all the essentials.
3. The species population recovers in natural environment.
4. Both (b) and (c).

4. Conditions maintained in seed banks for orthodox seeds are:

1. Low moisture content.
2. Anaerobic conditions.
3. Low temperature.
4. All of these.

5. Assertion: Animal species which have become extinct in wild continue to be maintained in zoological parks.

Reason: Captive breeding is the conservation of those cases where these is no realistic chance of in-situ survival.

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Give information about primary and secondary lymphoid organ ### Explain lymphatic organs of human lymphatic system. (Diagram is not required)

What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.

Read the following and answer any four questions from (i) to (v) given below:
The Kakapo is the world's largest and heaviest parrot, found only in New Zealand. It is unusual in that it is nocturnal, flightless and ground-dwelling. It is an excellent climber of trees, has strong legs that allow it to "jog" several kilometres in a single trip, and has mossy green plumage mottled with brown and yellow. The Kakapo is also critically endangered as of now, there were only few known living individuals left.

1. Which could be the possible reason for Kakapo to be well-adapted to its environment prior to the arrival of humans in New Zealand?

1. Kakapo was active only in the night when its potential predators would not be out for hunting.
2. The Kakapo would likely be well-camouflaged among the forest foliage due to its greenish plumage.
3. It was able to effectively hunt for food in the night.
4. All of these.

2. When humans started to settle in New Zealand, they took with them non-native animals, including mammals such as cats, dogs and stoats. By which of the following ways, human settlement likely contributed to a near decimation of Kakapo populations in New Zealand?

1. Habitat destruction.
2. Alien species invasion.
3. Pollution.
4. Both (a) and (b).

3. All known survived Kakapo have been relocated by the New Zealand government to three predator-free islands, where they are monitored year round by staffs and volunteers to ensure that the birds are safe, healthy and well-fed. The extremely low population of Kakapo is a hurdle to the species becoming viable in the long term, despite such dedicated conservation efforts. This is because.

1. The small population results in very small gene pool.
2. There would be very Ii mited genetic diversity among the resulting offspring.
3. Of reduced capacity of the species to adapt and survive changes in the environment.
4. All of these.

4. The reasons behind conserving biodiversity have been grouped into which of the following categories?

1. Narrowly utilitarian.
2. Broadly utilitarian.
3. Ethical.
4. All of these.

5. One of the ex situ conservation methods for endangered species is:

1. Wildlife sanctuaries.
2. Biosphere reserves.
3. Cryopreservation.
4. National parks.

Read the following and answer any four questions from (i) to (v) given below:
Wetlands are called Ramsar sites because the first international convention on their conservation was held in Ramsar in Iran in 1971. Wetlands or Ramsar sites are low lying marshy areas which get filled up during rains due to runoff and overflow from other water bodies. They are often considered to be waste lands which are used as dumping areas and filled up to recover land for various constructions activities. As a result, a large number of wetlands have disappeared.

1. Select the incorrect match of wetland and its location.

	Wetland	Location
(a)	Harike	Punjab
(b)	Chandra Tai	H.P.
(c)	Bhoj	M.P.
(d)	Ashtamudi	Odisha

2. Migratory bird flamingo breeds in which of the following wetlands?

1. Bhitarkanika Mangroves.
2. Rann of Kutch.
3. Harike.
4. Chandra Tal.

3. Which of the following is not an importance of wetlands?

1. They are an important source of recharging groundwater.
2. They provide protection from floods.
3. They are good source of siltation and purification of water.
4. None of these.

4. Which of the following wetland ecosystem is highly acidic and has a accumulation of decomposed plants known as peat?

1. Bog
2. Mangrove
3. Estuary
4. Watershed

5. The mangroves of Bhitarkanika are famous for:

1. Rare migratory waterbirds.
2. Nesting sites for endangered olive ridley turtles.
3. Prawn cultivation.
4. All of these.

Read the following and answer any four questions from (i) to (v) given below:
In testis, the immature male germ cells produce sperms by spermatogenesis that begins at puberty. It occurs in the seminiferous tubules of the testes. Seminiferous tubules are lined by germinal epithelium. Study the schematic representation of spermatogenesis and answer the following questions.

1. Which cell division occurs during multiplication phase?

1. Mitosis.
2. Meiosis I.
3. Meiosis II.
4. Both (b) and (c).

2. How many chromosomes are present in secondary spermatocyte and spermatid, respectively?

1. 46, 23
2. 46, 46
3. 23, 23
4. 23, XY

3. Transformation of L into M is known as:

1. Spermiation.
2. Spermateliosis.
3. Spermatogenesis.
4. None of these.

4. Select the correct option.

1. Type A spermatogonia grows to larger primary spermatocyte.
2. One spermatogonium forms two spermatids.
3. Spenniation is the release of sperms from seminiferous tubules.
4. Primary spermatocyte undergoes mitosis to form secondary spermatocytes.

5. Which hormone acts on spermatogonia to stimulate sperm production?

1. LH.
2. GnRH.
3. ABP.
4. FSH.

Differentiate between Monohybrid & Dihybrid Cross.