Question

what is meant by an animal or plant being in the same species

Answer 1

Here is a definition of the word "species"

Main Entry: [1]spe·cies
Pronunciation: 'spE-(")shEz, -(")sEz
Function: noun
Inflected Form(s): plural species
Etymology: Middle English, from Latin, appearance, kind, species, from specere to look —more at SPY
Date: 14th century
1 a : KIND, SORT b : a class of individuals having common attributes and designated by a common name; specifically : a logical division of a genus or more comprehensive class c : the human race : human beings — often used with the <survival of the species in the nuclear age> d (1) : a category of biological classification ranking immediately below the genus or subgenus, comprising related organisms or populations potentially capable of interbreeding, and being designated by a binomial that consists of the name of a genus followed by a Latin or latinized uncapitalized noun or adjective agreeing grammatically with the genus name (2) : an individual or kind belonging to a biological species e : a particular kind of atomic nucleus, atom, molecule, or ion
2 : the consecrated eucharistic elements of the Roman Catholic or Eastern Orthodox Eucharist
3 a : a mental image; also : a sensible object b : an object of thought correlative with a natural object