Explanation

The epididymis is a tube-like structure located behind each testicle where sperm cells are stored, matured, and nourished before being transported to the vas deferens and eventually ejaculated.

Explanation

• Flukes (trematodes) and tapeworms (cestodes) are both types of parasitic flatworms (Platyhelminthes).
• They have a well-developed reproductive system, which allows them to produce large numbers of eggs and reproduce effectively in their host organisms.

Explanation

• Down's syndrome, also known as Trisomy 21, is a genetic disorder caused by the presence of an extra copy of chromosome 21.
• This occurs due to a process called nondisjunction, where the chromosomes fail to separate properly during cell division (meiosis), resulting in an extra copy of chromosome 21 being inherited.

Explanation

• The phrase "above board" is an idiomatic expression that means to be honest, transparent, and ethical in one's dealings, especially in business or financial matters.
• It implies that all actions and decisions are open and fair, with no hidden agendas or secrets.

Explanation

• Cytotoxic T cells are a type of T lymphocyte that plays a crucial role in eliminating infected cells or tumor cells from the body.
• They recognize and bind to specific antigens presented on the surface of infected cells or tumor cells, and then release cytotoxins, such as granzymes and perforin, which form pores in the plasma membrane of the target cell, leading to cell lysis and death.

Explanation

• Fishes are the first formed Chordates, which is a phylum of animals that includes vertebrates (animals with backbones) and some invertebrates (animals without backbones).
• Chordates are characterized by the presence of a notochord (a flexible, rod-like structure that provides support and stiffness) at some stage in their development.

Explanation

• The Genetic Balance Theory, also known as the "genic balance theory", was proposed by American geneticist Thomas Hunt Morgan to explain the complex mechanism of sex determination in Drosophila (fruit flies).
• According to this theory, the sex of an individual is determined by the balance of genetic factors, rather than by a single gene or chromosome.

Explanation

• A J-shaped growth curve is a characteristic of exponential growth, where the population grows rapidly and unchecked, with no limits or restrictions.
• This type of growth occurs when a population has unlimited resources, such as food, water, and space, and is able to grow at its maximum rate, known as its biotic potential.

Explanation

• Contractile vacuoles are specialized organelles found exclusively in protozoa, such as amoebae and paramecia.
• They are responsible for osmoregulation, removing excess water and ions from the cell to maintain proper cellular turgor pressure.
• Contractile vacuoles are able to contract and expand to expel water and waste from the cell.

Explanation

• The sentence should read: "Their daughters are truly interested in one of the rare species that inhabit those islands."
• "Inhabit" means to live or dwell in a place, which fits the context of the sentence.