Question

The single cell organism which do not have defined nucleus and organelles are

Answer 1

bacteria, eubacteria,arhaebacteria are some organisms which organisms of Kingdom protista having not well defined nucleus and single cell

Answer 2

Pʀᴏᴋᴀʀʏᴏᴛᴇs ᴀʀᴇ ᴏʀɢᴀɴɪsᴍs ᴡʜᴏsᴇ ᴄᴇʟʟs ʟᴀᴄᴋ ᴀ ɴᴜᴄʟᴇᴜs ᴀɴᴅ ᴏᴛʜᴇʀ ᴏʀɢᴀɴᴇʟʟᴇs. Pʀᴏᴋᴀʀʏᴏᴛᴇs ᴀʀᴇ ᴅɪᴠɪᴅᴇᴅ ɪɴᴛᴏ ᴛᴡᴏ ᴅɪsᴛɪɴᴄᴛ ɢʀᴏᴜᴘs: ᴛʜᴇ ʙᴀᴄᴛᴇʀɪᴀ ᴀɴᴅ ᴛʜᴇ ᴀʀᴄʜᴀᴇᴀ, ᴡʜɪᴄʜ sᴄɪᴇɴᴛɪsᴛs ʙᴇʟɪᴇᴠᴇ ʜᴀᴠᴇ ᴜɴɪϙᴜᴇ ᴇᴠᴏʟᴜᴛɪᴏɴᴀʀʏ ʟɪɴᴇᴀɢᴇs. Mᴏsᴛ ᴘʀᴏᴋᴀʀʏᴏᴛᴇs ᴀʀᴇ sᴍᴀʟʟ, sɪɴɢʟᴇ-ᴄᴇʟʟᴇᴅ ᴏʀɢᴀɴɪsᴍs ᴛʜᴀᴛ ʜᴀᴠᴇ ᴀ ʀᴇʟᴀᴛɪᴠᴇʟʏ sɪᴍᴘʟᴇ sᴛʀᴜᴄᴛᴜʀᴇ.