Nihongo no Oshaberi 日本語のおしゃべり

Hiragana ＆Katakana Usage
「Part 2」

Hiragana:
When writing kanji, katakana is used to indicate inflectional ends (meaning the part of the word when spoken that has the most attention to annunciation).

Examples:
行く　I-ku　Go
行かない　I-Kanai　Don't go
白い　Shiro-i　White
祭り　Matsu-ri　Festival

Hiragana can also be used to write word endings (gobi) which is called okurigana. Sometimes this includes more than just the inflectional ending of the word, but the actual stem (gokan) is written in hiragana.

Example:
新しい　Atara-shii　New
大きい　Ō-kī　　　Big
食べる　Ta-beru　　Eat
　　　幸せ　Shiawa-se　Happiness

Katakana
Names of Plants, and animals, especially when used in a scientific capacity.

Examples:
          ネズミ　   Nezumi　Mouse・Rat
セミ　  Semi　Cicada
マグロ　  Maguro　Tuna
                                       サクラ　  Sakura　Cherry Tree (The Species)
　　　   タンポポ　Tanpopo　Dandelion

There are however, exceptions to this rule.

Examples:
犬　Inu　Dog
　　　　桜　Sakura　Cherry Tree
　　　　　　　　　みかん　Mikan　Satsuma Orange(Mandarin)

Hope this is useful to you！
(-^〇^-)　こゆうきあいはら　(-^〇^-)