How is diversity in living world related to taxonomy?

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(a)

The spectrum of diversity in the living world can be known only through the study of taxonomy.

Why lichens are called dual organisms?

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(a)

Lichens are dual organisms which contain a fungus or mycobiont and an alga or phycobinot.

Virus cannot grow on non-living culture medium. Give reason

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(a)

A virus cannot grow on non-living culture medium because it needs living cells for its metabolism and multiplication.

Why two kingdom classification continued to be used for a long time?

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(a)

Classification of organisms into plants and animals was easily done and was easy to understand.

Why Seeds remain exposed in gymnosperms?

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(a)

Seeds in gymnosperms remain exposed over the surface of the megasporophylls.This is because megasporophylls are not folded to form pistils like in angiosperms.

How does pollination occur in gymnosperms and how the pollen grains approach ovules?

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(a)

Pollination(by wind) in Gymnosperms is direct, as stigma is absent. the pollen grain reach the micropylar ends of ovules directly.

Give example of two unisexual animals

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(a)

Frog and birds.

What is pseudo segmentation?

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(a)

In tapeworms, body is divided into number of segments called proglottids that are budded off from the neck Each segment is able to perform all the vital function of body. This type of segmentation is called pseudo metamerism or pseudo segmentation.

Why pneumatic bones are present in birds?

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(a)

The empty space in pneumatic bones helps in weight reduction of skeleton in birds.It is a kind of flight adaptation in birds

Why the heartwood's colour is dark?

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(a)

The dark colour is due to the accumulation of secondary metabolities like tannins, gums, oils and resins, etc.,in the wood tissue. 

Certain epidermal adaxial cells along the midrib modify themselves to large , empty, colurless cells.Name these

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(a)

These cells are called bulliform cells.

What is the property of glandular epthelium ?

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(a)

It has secretory function

Why the bone is the hardest tissue in the body?

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(a)

The matrix of the bone is through and contains a protein called ossein which makes it hard . It has mineral deposits of calcium and phisphates

How does earthworm spoll the playgrounds?

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(a)

The earthworms make burrows in the soil of playground. This spoils the ground.

Which part of earthworm's body produces ootheca and what does it contain?

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(a)

Ootheca is produced by clitellum. Mature sperms, eggs and nutritive fluid are deposited in it.

Which layer of cell envelope is sticky in nature? Also give another name for this layer.

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(a)

The sticky layer of cell envelope is called glycocalyx. It is also known as mucilage sheath.

It is said that one cell cycle of cell division in human cells (eukaryotic cells) takes 24 hours. Which phase of the cycle, do you think occupies the maximum part of the cell cycle.

1

(a)

Interphase.

If a tissue has 1024 cells at a given time, how many cycles of mitosis had the original parental single cell undergone?

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(a)

Ten cycles of mitosis.

Can there be mitosis without DNA replication in ‘S’ phase?

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(a)

Mitosis cannot occur without DNA replication in S-phase because the trigger for mitosis takes place due to the disturbance in nucleocytoplasmic ratio caused by DNA replication in S-phase.

Meiosis is essential in sexually reproducing organisms.Why?

1

(a)

Meiosis is essential in sexually reproducing organisms because it keeps the chromosomes number constant.

Deficiency of nitrogen in plants induces stems, petioles and lower leaf surface of plants to get purplish in appearance.Analyse the statement and the reason behind the fact. 

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(a)

The appearance of purplish colour in different parts of plant occurs due to accumulation of anthocyanin.

Where do the electrons move from the electron acceptor of PS-II in the Z-Scheme.

1

(a)

The electrons move to PS-I from the electron acceptor of the PS-II in the Z-scheme.

Name the inhibitor of oxidative phosphorylation

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(a)

Oligomycin.

What happens if the meristematic cells ever cease to divide?

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(a)

If meristematic cells cease to divide, the growth of the plant will be hindered and will undergo a period of dormancy depending upon the seasonal changes in the climate.

How is negative pressure breathing helpful for mammals?

1

(a)

It allows the mammals to eat and breathe at the same time.