5. Why do thorns and spines exist? * O To stop animals from eating plants
To stop insects from pollinating
To stop people from looking at plants
O To help plants stay standing upright and give them their shape

to stop animals from eating plants

Explanation:

the thorns and spines help protect the plant for example if we touch the plant it hurts same goes with animals

A. To stop animals from eating plants

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation: