Tag: biology

Quizzes (1160) Questions (12174)

Questions Related to biology

Multiple choice biology health and hygiene minerals and vitamins nutrition and diet role of various nutrients

A bacterial population contains a mixture of wild type and leucine auxotrophs. From this mixture, the leucine auxotrophs can be enriched by growing the mixture in minimal medium supplemented with 

  1. leucine

  2. penicillin

  3. leucine and penicillin

  4. chloramphenicol
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Penicillin kills actively growing cells by inhibiting cell wall synthesis. Wild type cells grow in minimal medium and are killed by penicillin, whereas leucine auxotrophs cannot grow without leucine and thus remain dormant, surviving penicillin selection.

Multiple choice biology health and hygiene minerals and vitamins nutrition and diet role of various nutrients

Our hair and nails are composed of _________.

  1. Carbohydrates

  2. Proteins

  3. Vitamins

  4. Fat
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Hair and nails are made up of dead squamous cells which are called as keratinocytes. It consists of a protein known as keratin and is present in hair, nails and skin. It helps in protection as composed of intact cells.
So, the correct answer is 'Proteins'.
Multiple choice biology respiration in organism human respiration the mechanism of breathing breathing and its movements

Microscopic pores in plants through which they expire air are called

  1. Stigma

  2. Thalamus

  3. Gills

  4. Stomata
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A.Stigma - the terminal part of the gynoecium is called stigma.
B.Thalamus - The upper exapanded structure present at the tip of the pedicle.
C.Gills - the paired respiratory organ of fish and some amphibians, by which oxygen in extracted from water flowing over surfaces within or attached to the walls of the pharynx.
 D.stomata - minute pores present on the epidermis of aerial organs meant for transpiration
So, the correct option is 'stomata'.
Multiple choice biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

Both chasmogamous and cleistogamous flowers are present in

  1. Helianthus

  2. Commelina

  3. Rosa

  4. Gossypium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Commelina produces two types of flower chasmogamous flowers which are similar to the flower of other species with exposed anthers and stigma, and cleistogamous flowers which do not open at all. In such flowers, the anthers and stigma lie close to each other. When anthers dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, cleistogamous flowers are invariably autogamous as there is no chance of cross-pollen landing on the stigma. Cleistogamous flowers assure seed-setting even in the absence of pollinators. 

So, the correct answer is 'Commelina'.

Multiple choice biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

How can plants prevent self pollination?

  1. Plants should produce bisexual flowers

  2. Pistil should have increased receptivity for pollens from same plant

  3. Stamen and pistil mature at different times

  4. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plants prevent self-pollination by following methods:-

i) Making stamen and pistil mature at different times known as incompatibility.
ii) By producing unisexual flowers.
iii) Pollen release and stigma receptivity are not synchronised.
So, the correct option is 'Stamen and pistil mature at different times'.

Multiple choice biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

Flowering plants have developed certain outbreeding devices to discourage self-pollination and encourage cross-pollination. One of these is not an example of such outbreeding device.

  1. Dicliny

  2. Dichogamy

  3. Herkogamy

  4. Cleistogamy
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cleistogamous flowers are intersexual. They remain closed causing self-pollination. Cleistogamy occurs late in the flowering season in some plants. e.g., Commelina, balsam, Oxalis, Viola. These plants possess both chasmogamous and cleistogamous flowers. In cleistogamous flowers, the anthers dehisce inside closed flowers. The growth of style brings the pollen grains in contact with stigma. Cleistogamy ensures self-pollination. So, the correct answer is 'Cleistogamy'.

Multiple choice biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

Advantage of cleistogamy is ..................

  1. More vigorous offspring

  2. Non-dependence on pollinators

  3. Vivipary

  4. Higher genetic variability
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cleistogamy procedure do not depend on pollinators. It is because, cleistogamy is automatic self-pollination which describes the trait of certain plants to propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas and beans, this behaviour is most widespread in the grass family.

Multiple choice biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

The term used when anthers and stigmas of intersexual or perfect flowers ripen before the opening of buds is .............

  1. Chasmogamy

  2. Cleistogamy

  3. Immature pollination

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cleistogamy or automatic self-pollination describes the trait of certain plants to propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas and beans, this behaviour is most widespread in the grass family. The principal advantage of cleistogamy is that it requires less plant resources to produce seeds than does chasogamy because development of petals, nectar and large amounts of pollen are not required. This efficiency makes cleistogamy particularly useful for seed production on unfavourable sites or adverse conditions.

Multiple choice biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

In which of the following cleistogamous flowers are present?

  1. Balsam

  2. Arachis

  3. Commelina

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cleistogamy is a type of self-pollination occurs in closed flower in which transfer of pollen grain from an anther to stigma when they lie close to each other in a flower e.g., Balsam, Arachis and Commelina. 

Thus, the correct answer is option D.

Multiple choice biology pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

Self pollination is prevented by .............

  1. Dichogamy

  2. Self Sterility

  3. Hekrogamy

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Self pollination is a form of pollination that can occur when a flower has both stamen and a carpel in which the sultivar or species is self fertile and the stamens and the sticky stigma of the carpel contact each other in order to accomplish pollination. It is prevented by: dichogamy, self-sterility and hekrogamy. Dichogamy - having pistils and stamens that mature at different times, thus promoting cross-pollination rather than self pollination. Herkogamy - common strategy employed by angiosperms to reduce sexual interference between male (anthers) and female (stigma) function.