- abapikal
- accessorychromosome
- abcauline
- abioseston
- aboral
- acanthopore
- acidophilous
- acidophily
- accumbent
- actiniform
- actinoblast
- aculeateform
- aculeus
- acyesis
- acidofuge
- actinospore
- actinula
- adience
- adnexed
- aerenchyma
- aglomerular
- aglossate
- alisphenoid
- allelomorph
- aheliotropic
- allanto-chorion
- allele
- allometry
- allomorphism
- ambulacra
- amebocyte
- amphicyte
- amphidetic
- amphigenesis
- amphisternum
- amphithecium
- amylose
- amylum
- anaerobiosis
- anaphasis
- anaphragmic
- anaphysis
- anaplasm
- anaschistic
- ancestrula
- aneuploid
- aneuploidy
- annulus
- anidian
- animal starch
- amphidisc
- amphiodont
- amphispore
- amphistyly
- amphitropous
- amplectant
- anacanthous
- anaphyte
- anaplasia
- anastates
- anatoxin
- anatrepsis
- antidromic
- ancophilous
- andrangium
- androcyte
- androgamone
- androplasm
- androsome
- androspermium
- anemospore
- aneusomaly
- aneuspore
- anlage
- antimiotic
- aplacental
- apoenzyme
- apomict
- aposome
- apostaxis
- archenteron
- arrhenokaryon
- astropyle
- asyngamic
- athermobiotic
- athrocytosis
- atmobiosis
- arbovirus
- archicarp
- arthromere
- aseptate
- astelic
- astrocentre
- astrosphere
- asyngamy
- astroblast
- asynapsis
- athermobiosis
- atractoid
- auriularia