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Sexual reproduction The cell The advantages
THE SEX CHROMOSOMES
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100 females ABCDE AbCDE aBCDE antlers appear become birds and moths Bonellia boys breeding season bright colours castration chapter chevrotain colour-blindness concerned contraception copulation copulatory organ develop effect embryos evolution fact factors female-producing fertilized eggs formed freemartin fruit-fly Gametes germ cells girls glands gonads groups grow gynandromorphism halved number hermaphrodite higher animals inherited intersexes large number male and female male characters male sex mammals mankind many-celled animals marriage mated matter moiety mother natural selection normal number of chromosomes number of males offspring ovariotomy ovary pair of chromosomes Paramecium parent parthenogenesis polar body primitive probably produced promiscuity race reason Red-eyed female reducing division reproductive organs result secrete sex characters sex chromo sex chromosome sex determination sex ratio sex-intergrade sexual abnormality sexual characters sexual instinct sexual reproduction sexual selection single-celled animals species sperms sperms and eggs takes place tend testicular testis theory tissue tube types of sperm whereas White-eyed women