Which organism is a producer in this ecosystem? Fox Weasel Hawk Thrush Mouse Rabbit Squirrel Caterpillar Grass Shrubs Mushroom Shrubs

It could be shrubs or grass

Explanation:

Producers in ecosystems are autotrophic organisms, that means organisms that can synthesise their own food and do not rely on other organisms to provide food to them. Plants do this via photosynthesis - therefore plants are the producers of ecosystems.

Herbivores (such as caterpillars and thrushes) are primary consumers. Carnivores (such as weasels and foxes) are secondary/tertiary consumers, depending on the number of trophic levels.

G3P is converted into RuBP. The enzyme rubisco speeds up the reaction.