Tag: natural selection

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Questions Related to natural selection

Multiple choice biology selection and evolution theory of natural selection natural selection evidence for evolution

Choose the correct answers from the alternatives given.
............ sometimes occurs in situations where individuals of two previously isolated demes come back into sympatry.

  1. heterosis

  2. character displacement

  3. truncation selection

  4. frequency-dependent selection
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Character displacement is the term used to describe an evolutionary change that occurs when two similar species inhabit the same environment. This due to the geographical isolation.

So correct option is B, character displacement.

Multiple choice biology selection and evolution theory of natural selection natural selection evidence for evolution

State whether the following statements are true or false .
Transpiration takes place only through stomata in terrestrial plants.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transpiration can vary according to the type of structure involved. It is of four types:

1. Stomatal transpiration: Occurs through stomata. It is responsible for 50-97% of total transpiration.
2. Cuticular transpiration: Occurs through cuticle (a waxy layer that covers the epidermis of leaves and stems). Contributes 3-10% of the total transpiration.
3. Lenticular transpiration: Occurs through lenticels (aerating pores in the cork of woody stems). insignificant contribution to water loss.
4. Bark transpiration: Occurs through the bark of woody stem. Contributes to 1% of total transpiration.
So, the given statement is false.

Multiple choice biology selection and evolution theory of natural selection natural selection evidence for evolution

State whether the following statements are true or false.
DPD always has a positive value whereas water potential a negative value.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Diffusion pressure deficit (DPD) : It is the decrease in diffusion pressure of water in a solution over its pure state. It is always positive as the decrement of pressure cannot be negative.
The diffusion pressure of pure water is maximum and it continues to decrease as more and more solute is added into it.
Water potential is the potential energy of water compared to the potential energy of pure water. The potential energy of pure water is highest and it is assumed aa zero due to the absence of any impurity. Therefore, the potential energy of other water will be less than zero hence, expressed in negative in relation to pure water.
So the correct answer is 'True'
Multiple choice biology animal behaviour ethology natural selection coordination in human beings- chemical control endocrine system in humans

The main function of prolactin hormone is to

  1. Influence the activity of thyroid gland

  2. Control development of Graffian follicles

  3. Initiate and maintain secretion of milk by mammary gland

  4. Cause ejection of milk
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Prolactin, also called as luteotropic hormone (LTH) or luteotropin, is a protein hormone produced by the pituitary gland of mammals, that acts with other hormones to initiate secretion of milk by the mammary glands. 

Multiple choice biology animal behaviour ethology natural selection coordination in human beings- chemical control endocrine system in humans

Which of the following hormones stimulates the production of milk?

  1. LH

  2. Prolactin

  3. Oxytocin

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

Prolactin is the hormone that stimulates milk production. During pregnancy, prolactin stimulates growth of the breast, but high estrogen and progesterone secretion prevent milk production. After delivery, estrogen and progesterone levels drop, and prolactin stimulates the secretion of milk by alveolar cells in the breast.

Multiple choice biology animal behaviour ethology natural selection coordination in human beings- chemical control endocrine system in humans

Some hormones check the milk from being secreted by the mammary glands till the birth of young ones even though the glands are all prepared to do so. They are

  1. Progesteron and prolactin

  2. Prolactin and FSH

  3. Oestrogen and prolactin

  4. Oestrogen and progesteron
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Progesterone and prolactin check the milk from being secreted by the mammary glands till the birth of young ones even though the glands are all prepared to do so. Progesterone is a hormone released by the corpus luteum in the ovary. Changing progesterone levels can contribute to abnormal menstrual periods and menopausal symptoms. Prolactin is a hormone named originally after its function to promote milk production (lactation) in mammals in response to the suckling of young after birth. It has since been shown to have more than 300 functions in the body. These can be divided into a number of areas: reproductive, metabolic, regulation of fluids (osmoregulation), regulation of the immune system (immunoregulation) and behavioural functions.
At birth, prolactin levels remain high, while the delivery of the placenta results in a sudden drop in progesterone, oestrogen, and HPL levels.
Multiple choice biology animal behaviour ethology natural selection coordination in human beings- chemical control endocrine system in humans

Lemmings reduce their number by committing suicide every

  1. Eight years

  2. Alternate years

  3. Four years

  4. Two years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lemmings reduce their number by committing suicide every 4 years. It has been regarded as a collective suicide, conscious or involuntary, caused by overpopulation. In reality, being solitary rodents by nature, when the population booms, the stronger lemmings drive the weaker and younger ones off long before the food is depleted.

Therefore, the correct answer is option (C).

Multiple choice biology selection and evolution ethology animal behaviour natural selection

The idea of natural selection as the fundamental process of evolutionary changes was reached by:

  1. Charles Darwin and Alfred Russel Wallace in 1900

  2. Charles Darwin in 1866

  3. Alfred Russel Wallace in 1901

  4. Charles Darwin and Alfred Russel Wallace in 1859
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Charles Darwin and Alfred Russel Wallace independently formulated the theory of natural selection, which was presented to the Linnean Society in 1858 and published in Darwin's 'On the Origin of Species' in 1859.