Why apt removed php when I tried just to update apache?

I’m new with this yes,

I try to update apache2 to the latest llike this in my yml:

tasks:
- name: update packages
apt: name=apache2 state=latest update_cache=yes

It went fine but apache didn’t start anymore because php was messed up. Apt-log shows:

Start-Date: 2014-12-30 10:57:20
Commandline: /usr/bin/apt-get -y -o Dpkg::Options::=–force-confdef -o Dpkg::Options::=–force-confold install apache2
Install: apache2-mpm-itk:amd64 (2.2.22-1ubuntu1.7, automatic)
Upgrade: apache2:amd64 (2.2.22-1ubuntu1.4, 2.2.22-1ubuntu1.7), apache2.2-common:amd64 (2.2.22-1ubuntu1.4, 2.2.22-1ubuntu1.7), apache2.2-bin:amd64 (2.2.22-1ubuntu1.4, 2.2.22-1ubuntu1.7)
Remove: libapache2-mod-php5:amd64 (5.3.10-1ubuntu3.15), apache2-mpm-prefork:amd64 (2.2.22-1ubuntu1.4)
End-Date: 2014-12-30 10:57:28

… so it removed php5. When I installed libapache2-mod-php5:amd64 back, it works again.

What did I do wrong? How can I update one package and it’s required dependencies correctly? I mean, if there is gonna be for example a security issue with a one package, how to update only it and all the packages that are related but not the whole system?

Thanks.