| law of partial pressures | Each gas in a mixture of gases exerts a pressure proportionate to the percentage of the gas and independent of the presence of the other gases present. Synonym: law of partial pressures. (05 Mar 2000) |
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| pili, sex | Filamentous or elongated proteinaceous structures which extend from the cell surface in gram-negative bacteria that contain certain types of conjugative plasmid. These pili are the organs associated with genetic transfer and have essential roles in conjugation. Normally, only one or a few pili occur on a given donor cell. this preferred use of "pili" refers to the sexual appendage, to be distinguished from bacterial fimbriae (fimbriae, bacterial), also known as common pili, which are usually concerned with adhesion. (12 Dec 1998) |
| primary sex characters | The sex glands, testes or ovaries, and the accessory sex organs. (05 Mar 2000) |
| safe sex | Sexual practices that limit the risk of transmitting or acquiring an infectious disease via exchanges of semen, blood, and other bodily fluids, e.g., use of a condom, mutual masturbation, and avoidance of anal intercourse. (05 Mar 2000) |
| heterogametic sex | <biology> The gender which has two different sex chromosomes. For example: In humans, the male is heterogametic because he is XY (has an X chromosome and a Y chromosome). In birds, the female is heterogametic because she is WZ (has a W chromosome and a Z chromosome). Compare: homogametic sex. (09 Oct 1997) |
| secondary sex characters | Those character's peculiar to the male or female that develop at puberty, e.g., the beard of men and the breasts of women. (05 Mar 2000) |
| homogametic sex | <genetics> The gender which has two copies of the same sex chromosome. For example: In humans, the female is homogametic because she is XX (has two copies of the X chromosome). In birds, the male is homogametic because he is ZZ (has two copies of the Z chromosome). Compare: heterogametic sex. (09 Oct 1997) |
| sex | 1. The distinguishing peculiarity of male or female in both animals and plants; the physical difference between male and female; the assemblage of properties or qualities by which male is distinguished from female. 2. One of the two divisions of organic beings formed on the distinction of male and female. 3. <botany> The capability in plants of fertilizing or of being fertilized; as, staminate and pistillate flowers are of opposite sexes. One of the groups founded on this distinction. The sex, the female sex; women, in general. Origin: L. Sexus: cf. F. Sexe. Source: Websters Dictionary (01 Mar 1998) |
| sex attractants | Pheromones that elicit sexual attraction or mating behaviour usually in members of the opposite sex in the same species. (12 Dec 1998) |
| sex behaviour | Sexual activities of humans. (12 Dec 1998) |
| sex behaviour, animal | Sexual activities of animals. (12 Dec 1998) |
| sex cell | A spermatozoon or an ovum. Synonym: germ cell. (05 Mar 2000) |
| sex characteristics | Those characteristics that distinguish one sex from the other. The primary sex characteristics are the ovaries and testes and their related hormones. Secondary sex characteristics are those which are masculine or feminine but not directly related to reproduction. (12 Dec 1998) |
| sex chromatin | Condensed chromatin of the inactivated X chromosome in female mammals (Barr body). (18 Nov 1997) |
| sex chromosome | <genetics> Chromosome that determines the sex of an animal. In humans, where the two sex chromosomes (X and Y) are dissimilar, the female has two X chromosomes and the male is heterogametic (XY). <zoology> In birds, the opposite is the case, the male being XX and the female XY, in many organisms, there is only one sex chromosome and one sex is XX, the other X0. A portion of the X and Y chromosomes is similar and is known as the pseudoautosomal region. (14 Oct 1997) |