IB DP Biology D3.1 Reproduction

Which is the primary relative advantage of sexual reproduction over asexual reproduction?

• It is faster and produces more offspring quickly.

• It requires only one parent, making it simpler.

• It produces offspring with new gene combinations, providing variation for adaptation.

• It produces genetically identical clones adapted to an existing environment.

Answer explanation

The primary advantage of sexual reproduction is that it produces offspring with new gene combinations, which enhances genetic variation. This variation is crucial for adaptation to changing environments, unlike asexual reproduction.

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NGSS.HS-LS3-2

An organism that reproduces asexually is best suited for an environment that:

• Is rapidly changing or unstable.

• Is stable and predictable.

• Requires high rates of mutation.

• Contains many different niches.

Answer explanation

An organism that reproduces asexually benefits from a stable and predictable environment, as it allows for consistent conditions that favor the survival of its offspring without the need for genetic variation.

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NGSS.MS-LS2-4

What is the direct consequence of the fusion of gametes during the sexual life cycle?

• Reduction of the chromosome number by half.

• Maintenance of genetic continuity by creating identical cells.

• Production of a zygote with new combinations of alleles.

• Breaking up of parental allele combinations through crossing over.

Answer explanation

The fusion of gametes results in the formation of a zygote, which contains a unique combination of alleles from both parents, leading to genetic diversity in the offspring.

Tags

NGSS.HS-LS3-2

The primary role of meiosis in the sexual life cycle is to:

• Increase the number of chromosomes in the gametes.

• Allow for the production of diploid cells.

• Halve the number of chromosomes and break up parental combinations of alleles.

• Produce genetically identical cells for growth.

Answer explanation

The primary role of meiosis is to halve the chromosome number in gametes, ensuring genetic diversity by breaking up parental combinations of alleles, which is essential for sexual reproduction.

Which is the prime difference between male and female gametes that determines the differences in reproductive strategies?

• The female gamete is motile, while the male gamete is stationary.

• The male gamete is smaller and travels to the larger female gamete.

• The male gamete is diploid, while the female gamete is haploid.

• The male gamete contains more food reserves.

Answer explanation

The prime difference is that the male gamete is smaller and mobile, allowing it to travel to the larger, stationary female gamete. This size and mobility influence reproductive strategies significantly.

Following from the size difference in gametes, a male reproductive strategy typically involves:

• The production of a small number of large gametes.

• Extensive parental investment after fertilization.

• The production of a very large number of small, mobile gametes.

• Internal development of the zygote.

Answer explanation

A male reproductive strategy typically involves producing a very large number of small, mobile gametes, maximizing chances of fertilization. This contrasts with females, who produce fewer, larger gametes.

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NGSS.HS-LS4-2

What is the primary function of the epididymis in the male reproductive system?

• Production of testosterone.

• Storage and maturation of sperm.

• Production of seminal fluid.

• Site of fertilization.

Answer explanation

The primary function of the epididymis is the storage and maturation of sperm. It allows sperm to develop and gain motility before they are transported during ejaculation.

Which structure in the female reproductive system is the normal site of fertilization?

• Ovary

• Uterus

• Cervix

• Fallopian tube (oviduct)

Answer explanation

The Fallopian tube (oviduct) is the normal site of fertilization, where the sperm meets the egg after ovulation. The ovary produces the egg, but fertilization occurs in the Fallopian tube.

During the menstrual cycle, the surge in which hormone triggers ovulation?

• Progesterone

• Follicle-stimulating hormone (FSH)

• Luteinizing hormone (LH)

• Oestradiol

Answer explanation

The surge in luteinizing hormone (LH) is crucial for triggering ovulation during the menstrual cycle. While other hormones play roles, it is LH that directly initiates the release of the egg from the ovary.

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NGSS.HS-LS1-3

Which hormone, produced by the developing follicle, exerts positive feedback on the pituitary gland to increase the secretion of LH just before ovulation?

• Oestradiol

• Progesterone

• Testosterone

• Cortisol

Answer explanation

Oestradiol, produced by the developing follicle, stimulates the pituitary gland to release more LH, leading to the LH surge that triggers ovulation. This positive feedback mechanism is crucial for the ovulatory process.

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NGSS.HS-LS1-3